# CommandSection

title: CONFIGURATION LANGUAGE
content:
<b><I>bird</I></b> uses its own powerful domain-specific configuration language, typically defined in the <b><I>bird.conf</I></b> file. This language enables highly granular control over routing policies, protocol settings, filtering rules, and more, providing immense flexibility for complex routing scenarios.


title: HISTORY
content:
The BIRD project originated around 1998-1999 at the Faculty of Mathematics and Physics, Charles University in Prague, Czech Republic. It was developed to provide a robust, open-source routing daemon for the Linux platform, emphasizing modularity, extensibility, and advanced policy-based routing capabilities. It has since become a widely adopted solution in various network environments, including Internet Exchange Points (IXPs) and enterprise networks.


title: SYNOPSIS
content:
<b>blender</b> [<i>OPTIONS</i>] [<i>FILE</i>]<br><b>blender</b> -b [<i>FILE</i>] -o <i>//render/image_</i> -F <i>PNG</i> -E <i>CYCLES</i> -s <i>1</i> -e <i>250</i> -a<br><b>blender</b> -b [<i>FILE</i>] -P <i>script.py</i>


title: PARAMETERS
content:
<b><b>-b</b>, <b>--background</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Run in background (no GUI). Essential for rendering without the graphical interface, especially for batch processing.<br><br><b><b>-o</b> <i>&lt;path&gt;</i>, <b>--render-output</b> <i>&lt;path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the output path for rendered images or animations. Path can be relative (e.g., <i>//render/</i>) or absolute.<br><br><b><b>-F</b> <i>&lt;format&gt;</i>, <b>--render-format</b> <i>&lt;format&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the output file format (e.g., <i>PNG</i>, <i>JPEG</i>, <i>FFMPEG</i>, <i>OPEN_EXR</i>). Affects the type of file saved.<br><br><b><b>-E</b> <i>&lt;engine&gt;</i>, <b>--engine</b> <i>&lt;engine&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Select the render engine to use (e.g., <i>CYCLES</i>, <i>BLENDER_EEVEE</i>, <i>BLENDER_WORKBENCH</i>).<br><br><b><b>-s</b> <i>&lt;start_frame&gt;</i>, <b>--start-frame</b> <i>&lt;start_frame&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the start frame number for an animation render.<br><br><b><b>-e</b> <i>&lt;end_frame&gt;</i>, <b>--end-frame</b> <i>&lt;end_frame&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the end frame number for an animation render.<br><br><b><b>-f</b> <i>&lt;frame&gt;</i>, <b>--frame</b> <i>&lt;frame&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Render a single specific frame number.<br><br><b><b>-a</b>, <b>--render-anim</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Render the full animation as defined by the start and end frames in the Blender file or overridden by <b>-s</b> and <b>-e</b>.<br><br><b><b>-P</b> <i>&lt;script.py&gt;</i>, <b>--python</b> <i>&lt;script.py&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Run the specified Python script within Blender's environment. Useful for automating complex tasks and data manipulation.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Print Blender version information and exit.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a summary of command-line options and exit.<br><br>


title: DESCRIPTION
content:
<i>Blender</i> is a professional, free, and open-source 3D computer graphics software toolset used for creating animated films, visual effects, art, 3D printed models, motion graphics, interactive 3D applications, and video games.<br><br>While primarily a graphical application, the <b>blender</b> command-line interface provides powerful capabilities for automation, batch processing, and integration into render farms. Users can leverage it for tasks such as opening <i>.blend</i> files, rendering single frames or entire animations in headless mode (without a GUI), executing Python scripts for advanced customization, and converting between various file formats. This makes <b>blender</b> a versatile tool not just for interactive design but also for server-side processing and continuous delivery pipelines.


title: CAVEATS
content:
Command-line rendering, especially with complex scenes or high-quality settings, can be extremely resource-intensive (CPU, RAM, GPU). Ensure your system meets the necessary hardware requirements. Python scripting requires understanding Blender's specific Python API (<i>bpy</i>). Missing dependencies for specific render engines (e.g., CUDA or OpenCL drivers for GPU rendering) can lead to errors or fallbacks to CPU rendering.


title: PYTHON SCRIPTING FOR AUTOMATION
content:
The ability to run Python scripts via the command line (using <b>-P</b> or <b>--python</b>) is one of <b>blender</b>'s most powerful features. This allows users to automate repetitive tasks, create custom tools, perform complex data manipulation on <i>.blend</i> files, and integrate Blender into larger software pipelines without needing to interact with the GUI. Scripts have full access to Blender's API (<i>bpy</i>), enabling control over almost every aspect of a scene, object, or render setting.


title: HEADLESS RENDERING FOR RENDER FARMS
content:
Running <b>blender</b> in background mode (<b>-b</b> or <b>--background</b>) is crucial for setting up render farms or automated rendering workflows. This allows rendering to occur on dedicated servers without the overhead of a graphical interface, making it efficient for batch rendering large numbers of frames or complex animations across multiple machines. It's a cornerstone for professional animation studios and VFX houses utilizing Blender.


title: HISTORY
content:
<i>Blender</i> was initially developed as an in-house application by the Dutch animation studio NeoGeo in 1994, with the primary author being Ton Roosendaal. In 1998, it was released to the public as freeware. When NeoGeo went bankrupt in 2002, the source code was released under the GNU General Public License (GPL) following a successful crowdfunding campaign. Since then, it has been continuously developed by the Blender Foundation and a global community, evolving into one of the most comprehensive and widely-used open-source 3D software packages.


title: SYNOPSIS
content:
blurlock [OPTIONS]<br><br><i>Note: The exact syntax and available options are highly dependent on the specific user-created <b>blurlock</b> script being used.</i>


title: PARAMETERS
content:
<b><b>-h</b> or <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help information for the script.<br><br><b><b>-s</b> or <b>--screenshot-only</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Takes a screenshot and blurs it, but does not invoke <b>i3lock</b>.<br><br><b><b>-r &lt;radius&gt;</b> or <b>--radius &lt;radius&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the blur radius for the image processing, controlling the intensity of the blur.<br><br><b><b>-p &lt;pixelate_factor&gt;</b> or <b>--pixelate &lt;pixelate_factor&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Applies a pixelation effect instead of or in addition to blur.<br><br><b><b>-c &lt;color&gt;</b> or <b>--color &lt;color&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a specific color for the lock screen overlay or indicator (e.g., <b>#000000FF</b>).<br><br><b><b>-u</b> or <b>--no-unlock-indicator</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables the unlock indicator or text overlay on the lock screen.<br><br>


title: DESCRIPTION
content:
<i>blurlock</i> is not a standalone, pre-installed Linux command. Instead, it refers to a common shell script or method used by Linux users, especially those using tiling window managers like <b>i3</b> or <b>Sway</b>, to create a visually appealing lock screen. The core idea is to take a screenshot of the current desktop, apply a blur effect to it using image manipulation tools (like ImageMagick's <i>convert</i>), and then use this blurred image as the background for the <b>i3lock</b> utility. This provides a "blur-behind" effect, obscuring the sensitive screen content while maintaining a thematic visual element. The specific implementation of a "blurlock" script can vary widely depending on the user's preferences and the tools available, often incorporating options for different blur levels, pixelation, or custom lock screen indicators.


title: CAVEATS
content:
<b>blurlock</b> is not a standard Linux command; it refers to a common <i>scripting pattern</i> or <i>custom utility</i>.<br>Requires external dependencies such as <b>scrot</b> (or <b>grim</b> for Wayland), <b>ImageMagick</b> (for <i>convert</i>), and <b>i3lock</b> (or <b>swaylock</b> for Wayland).<br>The functionality and options are entirely dependent on how the specific <b>blurlock</b> script is implemented by the user.<br>Performance may vary based on screen resolution and system resources, as it involves real-time image processing.<br>Not suitable for environments where <b>scrot</b> or <b>i3lock</b> are not available or where Wayland is in use (requiring <b>grim</b> and <b>swaylock</b> alternatives).


title: IMPLEMENTATION OVERVIEW
content:
Most <b>blurlock</b> scripts follow a similar pipeline:<br>1. Capture the screen: Use <b>scrot -o /tmp/screenshot.png</b> (or <b>grim</b> for Wayland).<br>2. Process the image: Apply blur using <b>convert /tmp/screenshot.png -blur 0x8 /tmp/blurred.png</b> (the <i>0x8</i> indicates a sigma of 8 pixels for the Gaussian blur, adjustable). Other effects like pixelation (<b>-scale 10% -scale 1000%</b>) can also be applied.<br>3. Lock the screen: Call <b>i3lock -i /tmp/blurred.png</b> (or <b>swaylock</b> for Wayland) with the processed image as the background.<br>4. Clean up: Remove the temporary image files.


title: CUSTOMIZATION
content:
Users often extend <b>blurlock</b> scripts to include more sophisticated features, such as displaying system information, custom fonts, power indicators, or integrating with notification daemons. The flexibility of shell scripting allows for nearly limitless customization.


title: HISTORY
content:
The concept of blurring the screen before locking emerged as users sought more aesthetically pleasing and functional lock screens beyond simple black backgrounds. With the rise in popularity of tiling window managers like <b>i3wm</b>, which offer extensive customization, shell scripting became a natural way to achieve this. Early implementations combined <b>scrot</b> for screenshots and <b>ImageMagick</b>'s <i>convert</i> for image manipulation, piping the output to <b>i3lock</b>. This approach gained traction in communities like r/unixporn and various dotfile repositories, becoming a de facto standard for custom i3lock setups. While no single "blurlock" command was officially released, the term became a widely understood shorthand for this specific lock screen customization technique.


title: PARAMETERS
content:
<b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the help message and exits.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the program's version number and exits.<br><br><b><b>--debug</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts <b>bpytop</b> in debug mode for troubleshooting.<br><br><b><b>--full</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts with full CPU graphs, showing more detailed core usage.<br><br><b><b>--tty_mode</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces TTY mode, disabling mouse support and reducing some graphical features for compatibility.<br><br><b><b>--low_cpu</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces low CPU mode, similar to TTY mode but also reduces the update frequency of CPU graphs to save resources.<br><br><b><b>--config</b> <I>FILE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a custom configuration file path to use instead of the default.<br><br><b><b>--theme</b> <I>THEME_NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a custom theme by name. Themes must be present in the configured themes directory.<br><br><b><b>--preset</b> <I>PRESET_NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Applies a predefined layout or configuration preset.<br><br>


title: DESCRIPTION
content:
<b>bpytop</b> is a comprehensive and interactive resource monitor for Linux, macOS, and FreeBSD. It's a Python port of the popular <i>bashtop</i> and <i>btop</i> projects, designed to provide a rich graphical interface for monitoring system resources.<br><br>It displays real-time statistics for the processor, memory, disk I/O, network usage, and active processes. Key features include full mouse support, a customizable UI with themes, detailed process information including tree view and process filtering, and the ability to send signals to processes. <b>bpytop</b> aims for a visually appealing and intuitive user experience, making system monitoring both efficient and enjoyable. Its game-inspired menu system allows for easy navigation and configuration of various settings, offering a modern alternative to traditional tools like <i>top</i> or <i>htop</i>.


title: CAVEATS
content:
<b>bpytop</b> requires a Python 3 installation to run. While generally optimized, its rich graphical interface and continuous data updates can consume more CPU and memory resources compared to simpler terminal monitors like <i>top</i> or <i>htop</i> on systems with very limited resources. Full functionality, such as true color and mouse support, depends on the capabilities of the terminal emulator being used.


title: INTERACTIVE FEATURES
content:
Beyond mere display, <b>bpytop</b> offers extensive interactive capabilities. Users can navigate through processes, sort by different metrics, filter processes by name, and send various signals (e.g., <i>SIGTERM</i>, <i>SIGKILL</i>) directly from the interface. It also supports full mouse interaction for clicking buttons, selecting options, and scrolling, greatly enhancing usability in a terminal environment.


title: CUSTOMIZATION
content:
A strong point of <b>bpytop</b> is its high degree of customization. Users can tailor the interface with different color themes, adjust refresh rates, change graph scales, and configure which information panels are displayed. Settings are saved in a configuration file, allowing for persistent personalization across sessions.


title: HISTORY
content:
<b>bpytop</b> is part of a lineage of modern terminal resource monitors. It originated from <i>bashtop</i>, a monitor written in Bash. Subsequently, <i>btop</i> emerged as a C++ rewrite of <i>bashtop</i>, focusing on performance. <b>bpytop</b> then followed as a Python port of <i>bashtop</i>, aiming for greater portability and easier maintenance while retaining the visually rich and interactive user interface that made its predecessors popular. This evolution reflects an ongoing effort to combine powerful system monitoring with an engaging and user-friendly terminal experience.


title: SYNOPSIS
content:
<b>brctl</b> <i>command</i> [<i>bridge</i>] [<i>interface</i>] [<i>options</i>]<br><br>Common commands include:<br><b>brctl addbr</b> <i>&lt;bridge&gt;</i><br><b>brctl delbr</b> <i>&lt;bridge&gt;</i><br><b>brctl show</b><br><b>brctl addif</b> <i>&lt;bridge&gt;</i> <i>&lt;interface&gt;</i><br><b>brctl delif</b> <i>&lt;bridge&gt;</i> <i>&lt;interface&gt;</i><br><b>brctl stp</b> <i>&lt;bridge&gt;</i> <i>{on|off}</i><br><b>brctl setageing</b> <i>&lt;bridge&gt;</i> <i>&lt;time&gt;</i>


title: PARAMETERS
content:
<b>addbr <bridge></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Creates a new Ethernet bridge named <i>&lt;bridge&gt;</i>.<br><br><b>delbr <bridge></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Deletes the specified Ethernet bridge named <i>&lt;bridge&gt;</i>.<br><br><b>show</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists all existing bridges and their associated interfaces, providing a summary of their configuration.<br><br><b>addif <bridge> <interface></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Adds the network interface <i>&lt;interface&gt;</i> to the bridge <i>&lt;bridge&gt;</i>. This makes the interface part of the bridged network.<br><br><b>delif <bridge> <interface></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Removes the network interface <i>&lt;interface&gt;</i> from the bridge <i>&lt;bridge&gt;</i>.<br><br><b>stp <bridge> {on|off}</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables or disables Spanning Tree Protocol (STP) on the bridge <i>&lt;bridge&gt;</i>. STP prevents network loops.<br><br><b>setageing <bridge> <time></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the MAC address aging time (in seconds) for the bridge's forwarding database. MAC entries older than this time are removed.<br><br><b>showstp <bridge></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays detailed Spanning Tree Protocol (STP) information for a specified bridge.<br><br>


title: DESCRIPTION
content:
The command <b>br</b> is not a standard Linux command.<br>This analysis assumes <b>br</b> is a common typo for <b>brctl</b>, the <i>bridge control utility</i>. <br><br><b>brctl</b> is used to set up, maintain, and inspect Ethernet bridges in Linux. An Ethernet bridge acts as a software-defined network switch, allowing multiple network interfaces (physical or virtual) to be combined into a single logical interface. This enables communication between devices connected to different interfaces as if they were on the same physical network segment.<br><br>It is commonly employed in virtualization environments (e.g., KVM, LXC) to connect virtual machines or containers to the host network, enabling them to share network access or communicate with each other. It also supports Spanning Tree Protocol (STP) to prevent network loops and various parameters to fine-tune bridge behavior.


title: CAVEATS
content:
The command <b>br</b> itself is not a standard, standalone utility in most mainstream Linux distributions. This analysis covers <b>brctl</b>, which is the likely intended command.<br><br>Usage of <b>brctl</b> typically requires root privileges (e.g., using <b>sudo</b>). While still widely used and effective, some newer Linux network configurations, particularly with the <i>iproute2</i> suite (e.g., using <b>ip link add type bridge</b>), offer alternative and often more integrated ways to manage network bridges.


title: WHAT IS AN ETHERNET BRIDGE?
content:
An Ethernet bridge in Linux is a software implementation of a network switch. It operates at Layer 2 (Data Link Layer) of the OSI model. Its primary function is to forward network traffic between different connected network segments (interfaces) based on MAC addresses, effectively joining them into a single, larger logical network. This is fundamental for scenarios like virtual machine networking, where virtual network interfaces need to connect seamlessly to the host's physical network or to each other.


title: HISTORY
content:
The <b>brctl</b> utility is part of the <i>bridge-utils</i> package, which has been a staple in Linux networking for many years. It was the primary tool for managing software Ethernet bridges on Linux systems. With the advent of the <i>iproute2</i> suite, which introduced commands like <b>ip link</b>, modern Linux systems offer alternative and often more unified methods for network configuration. Despite this, <b>brctl</b> remains widely used and is still installed by default on many distributions due to its direct and simple interface for common bridge operations.


title: PARAMETERS
content:
<b><b>-a</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show all messages in the mailbox, regardless of whether they have been read. Note that for many modern implementations, this is the default behavior.<br><br><b><b>-c</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Print the character count for each message listed, following the sender and date information.<br><br><b><b>-l</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Print the line count for each message listed, following the sender and date information.<br><br><b><b>-s</b> <i>sender</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display only those messages that were sent by the specified <i>sender</i>. This allows for filtering mail summaries.<br><br><b><i>user</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the username whose mailbox should be inspected. If omitted, <b>bsd-from</b> defaults to the current user's mailbox.<br><br>


title: DESCRIPTION
content:
The <b>bsd-from</b> command is a utility designed to quickly scan a user's mail spool file, typically located at <i>/var/mail/$USER</i> or <i>/var/spool/mail/$USER</i>, for lines indicating the sender and date of mail messages.<br><br>It parses the mailbox file for lines beginning with "From ", which are characteristic of the traditional Unix <i>mbox</i> mail format. This provides a concise summary of incoming mail, allowing users to see who sent messages and when, without needing to open a full mail client.<br><br><b>bsd-from</b> is a re-implementation of the classic <i>from</i> command found on BSD Unix systems, providing compatibility and a simple command-line interface for rudimentary mail inspection. It is particularly useful in environments where mail is still delivered to local <i>mbox</i> files.


title: CAVEATS
content:
<b>bsd-from</b> is primarily designed for and works best with mailboxes stored in the traditional <i>mbox</i> format. It may not function correctly or provide meaningful output for mailboxes using modern formats like <i>Maildir</i>, or for mail accessed via IMAP/POP3 clients.<br><br>It only extracts the "From " envelope line and does not display full mail headers or message bodies.


title: MAILBOX FORMAT DEPENDENCY
content:
This command relies heavily on the mail spool file conforming to the <i>mbox</i> format, where each message starts with a line beginning "From " (with a space) followed by the sender's address and a timestamp. Without this specific format, the command may fail to parse messages correctly.


title: OUTPUT FORMAT
content:
The typical output for each message is a single line resembling: <br><i>From user@example.com Mon Jan 01 12:34:56 2023</i><br>When <b>-c</b> or <b>-l</b> options are used, the character or line count will be appended to this line.


title: HISTORY
content:
The <b>bsd-from</b> command is a Linux re-implementation of the original <i>from</i> command, which was a standard utility on BSD Unix systems since their early days. It served as a basic tool for users to quickly check their incoming mail. Its inclusion in Linux distributions, often as part of compatibility packages like <i>bsd-mailx</i>, ensures that traditional Unix scripts and workflows can continue to function, bridging the gap between older and newer system conventions. It represents a simpler era of mail management where mail was stored in plain text files directly on the system.


title: DESCRIPTION
content:
The <b>adventure</b> command launches a text-based interactive fiction game, a modern port of the original <i>Colossal Cave Adventure</i>. Developed in the 1970s, it's one of the earliest examples of interactive fiction and laid the groundwork for the adventure game genre. Players navigate a vast cave system by typing simple commands (e.g., 'go north', 'take key', 'open door') to explore rooms, solve puzzles, collect treasures, and overcome obstacles. The primary goal is to find all the treasures and return them to the starting location, known as the 'well house'. The game emphasizes exploration, logical deduction, and resource management within a purely textual environment, offering a unique and historically significant gaming experience.


title: CAVEATS
content:
This is a purely text-based game; interactions are solely through typed commands and descriptive text. Modern users accustomed to graphical interfaces might find the interface challenging. Game progress is typically saved in a file (e.g., <i>~/.adventure</i> or <i>adventure.dat</i>) and can be resumed later by simply running the command again.


title: GAMEPLAY BASICS
content:
Players interact with the game by typing natural language-like commands. The game responds with descriptions of the current location, available objects, or consequences of actions. Common commands include movement (e.g., 'north', 'n', 'go east'), interaction (e.g., 'take sword', 'drop keys'), and querying information (e.g., 'inventory', 'look'). Success requires careful reading, mapping, and creative problem-solving.


title: HISTORY
content:
The original <i>Colossal Cave Adventure</i> was created by Will Crowther in 1976 on a PDP-10, inspired by his caving hobby. Don Woods significantly expanded it in 1977. Its release sparked the interactive fiction genre and influenced countless later video games, including graphic adventure games and RPGs. The version provided by the <i>bsdgames</i> package is a modern, often updated port of this foundational work, maintaining its original spirit and gameplay.


title: PARAMETERS
content:
<b>-c string</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Reads commands from the provided 'string'.<br><br><b>-i</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Invokes the shell in interactive mode.<br><br><b>-s</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Reads commands from standard input.<br><br><b>-r</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Invokes the shell as a restricted shell, limiting certain operations for security.<br><br><b>-u</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Treats unset variables as an error, causing the shell to exit.<br><br><b>-v</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints shell input lines as they are read.<br><br><b>-x</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints commands and their arguments as they are executed (debug mode).<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help information for the shell.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information for the shell.<br><br>


title: DESCRIPTION
content:
The command '<I>bshell</I>' is <B>not a standard Linux command</B> found in most modern distributions. It is highly probable that the query refers conceptually to the <B>Bourne Shell</B>, for which the actual command is '<I>sh</I>'.<br><br>The Bourne Shell ('<I>sh</I>') is a foundational command-line interpreter for Unix-like operating systems, developed by Stephen Bourne at Bell Labs. It was the default shell on Unix systems until the mid-1980s and remains critically important, especially for scripting, due to its ubiquitous presence and POSIX compliance. '<I>sh</I>' provides a programming language to control program execution, offering features like variables, control flow (if/then/else, loops), function definitions, and I/O redirection. Many shell scripts begin with <I>#!/bin/sh</I> to ensure compatibility across different Unix and Linux systems. Modern Linux distributions often symlink <I>/bin/sh</I> to more advanced shells like <I>bash</I> or <I>dash</I>, but they generally maintain a high degree of <I>sh</I>-compatibility.


title: CAVEATS
content:
The command '<I>bshell</I>' itself is <B>not a standard or commonly recognized Linux command</B>. The information provided above pertains to the Bourne Shell, invoked via the command '<I>sh</I>', which is often conceptually referred to by its full name.<br><br>While '<I>sh</I>' is highly portable, its feature set is minimal compared to modern shells like <I>bash</I> or <I>zsh</I>. Common interactive conveniences like command history, tab completion, and advanced globbing are typically absent in a pure '<I>sh</I>' environment. Implementations of <I>/bin/sh</I> on modern systems may offer extensions but are designed to be strictly POSIX compliant when invoked as '<I>sh</I>'.


title: POSIX COMPLIANCE
content:
The Bourne Shell's syntax and behavior critically influenced the POSIX.1-2008 standard for shells, making '<I>sh</I>' a highly portable choice for shell scripting. Scripts written for '<I>sh</I>' are generally expected to function consistently across various Unix-like systems, ensuring maximum compatibility.


title: SHEBANG ('#!')
content:
Many shell scripts begin with the 'shebang' line: <B><I>#!/bin/sh</I></B>. This special line instructs the operating system to execute the script using the interpreter located at <I>/bin/sh</I>. This practice is crucial for ensuring that scripts are executed in a POSIX-compliant environment, regardless of the user's default interactive shell (which might be <I>bash</I>, <I>zsh</I>, etc.).


title: HISTORY
content:
The Bourne Shell, '<I>sh</I>', was developed by Stephen Bourne at Bell Labs and released in 1977 with Version 7 Unix. It was a significant improvement over its predecessor, the Thompson shell, by introducing advanced features like control flow constructs, functions, and robust signal handling, thereby transforming the shell into a powerful scripting language. Its syntax and design became the foundational basis for the POSIX shell standard, profoundly influencing all subsequent major Unix and Linux shells.<br><br>Although its direct interactive use has largely been superseded by more feature-rich shells, its legacy and paramount importance in shell scripting, especially for portable scripts, remain undiminished. The term '<I>bshell</I>' is sometimes used colloquially or historically to refer to the Bourne Shell, but the actual command invoked is '<I>sh</I>'.


title: SYNOPSIS
content:
<b>busctl</b> [<i>OPTIONS</i>...] <i>COMMAND</i> [<i>ARGUMENTS</i>...]<br><br>Common Commands:<br>  <b>busctl list</b> [<i>SERVICE</i>]<br>  <b>busctl status</b> [<i>SERVICE</i>]<br>  <b>busctl monitor</b> [<i>MATCH</i>...]<br>  <b>busctl call</b> <i>SERVICE PATH INTERFACE METHOD</i> [<i>SIGNATURE</i> [<i>ARGUMENTS</i>...]]<br>  <b>busctl get-property</b> <i>SERVICE PATH INTERFACE PROPERTY</i><br>  <b>busctl set-property</b> <i>SERVICE PATH INTERFACE PROPERTY SIGNATURE ARGUMENT</i><br>  <b>busctl introspect</b> <i>SERVICE PATH</i><br>  <b>busctl tree</b> [<i>SERVICE</i>]


title: PARAMETERS
content:
<b><b>--json</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Format output as JSON for machine parsing.<br><br><b><b>--no-pager</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not pipe output into a pager.<br><br><b><b>--no-legend</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not print the column legend or header lines.<br><br><b><b>--user</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Talk to the user's session D-Bus bus instead of the system bus.<br><br><b><b>--system</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Talk to the system D-Bus bus (this is the default).<br><br><b><b>--address=</b><i>ADDRESS</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Connect to the specified D-Bus address instead of the default system or user bus.<br><br><b><b>--show-machine</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show the machine name as the first column of the output, useful for `systemd-machined` integration.<br><br><b><b>list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;List names of D-Bus services and their process IDs (PIDs).<br><br><b><b>status</b> <i>SERVICE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show runtime status information about a D-Bus service, including its PID and associated unit.<br><br><b><b>monitor</b> [<i>MATCH</i>...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Monitor D-Bus messages (method calls, replies, signals) matching optional rules.<br><br><b><b>call</b> <i>SERVICE PATH INTERFACE METHOD</i> [<i>SIGNATURE</i> [<i>ARGUMENTS</i>...]]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Invoke a method on a D-Bus object with specified arguments and types.<br><br><b><b>get-property</b> <i>SERVICE PATH INTERFACE PROPERTY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Retrieve a property from a D-Bus object.<br><br><b><b>set-property</b> <i>SERVICE PATH INTERFACE PROPERTY SIGNATURE ARGUMENT</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set a property on a D-Bus object with a specified value and type.<br><br><b><b>introspect</b> <i>SERVICE PATH</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show available interfaces, methods, signals, and properties for a D-Bus object.<br><br><b><b>tree</b> [<i>SERVICE</i>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show a tree of available D-Bus objects for a specific service or all services.<br><br><b><b>cap-set</b> <i>SERVICE CAPABILITY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set a specific D-Bus capability for a service (typically for advanced use or debugging).<br><br>


title: DESCRIPTION
content:
<b>busctl</b> is a command-line utility used for introspecting, calling, and monitoring D-Bus. It is part of the <i>systemd</i> suite of tools and provides a powerful interface to interact with D-Bus services and objects. D-Bus is an inter-process communication (IPC) mechanism primarily used in Linux for communication between applications, particularly system services and desktop environments.<br><br>With <b>busctl</b>, users can:<br><ul><li>List active D-Bus services and their details.</li><li>Make method calls on D-Bus objects, including specifying arguments and types.</li><li>Get and set properties of D-Bus objects.</li><li>Monitor D-Bus traffic, including method calls, replies, and signals.</li><li>Introspect D-Bus objects to discover available interfaces, methods, signals, and properties.</li></ul>It simplifies D-Bus interaction, offering a more user-friendly interface compared to lower-level D-Bus tools or direct API usage, making it indispensable for system administrators and developers debugging D-Bus-related issues or exploring system functionality.


title: CAVEATS
content:
<b>busctl</b> requires a basic understanding of D-Bus concepts (bus names, object paths, interfaces, methods, signals, properties, signatures) to be used effectively.<br><br>Invoking methods or setting properties on system services can have significant system-wide effects and may require elevated privileges (e.g., `sudo`). Always exercise caution when making changes.<br><br>D-Bus object paths and interface names are case-sensitive. Typographical errors can lead to 'No such object' or 'No such interface' errors.<br><br>The <b>--json</b> output format is primarily intended for machine parsing and may not be as human-readable as the default output.


title: D-BUS DATA TYPES AND SIGNATURES
content:
D-Bus messages, arguments, and return values are strongly typed. <b>busctl</b> uses D-Bus <i>signatures</i> to specify argument types for method calls and property assignments. A signature is a string representing a sequence of types, e.g., 's' for string, 'i' for 32-bit integer, 'b' for boolean, 'd' for double, 'v' for variant, 'a(ss)' for an array of structs containing two strings. Understanding these signatures is crucial for correctly crafting <b>busctl call</b> and <b>busctl set-property</b> commands.<br><br>For complex types like arrays or structs, <b>busctl</b> expects arguments to be provided in a specific, space-separated format. For example, to pass an array of strings, you might use <i>'as' 2 'string1' 'string2'</i>, where 'as' is the signature, '2' is the count, followed by the elements. A dictionary (array of key-value pairs) might be 'a{sv}' 2 'Key1' 'Value1' 'Key2' 'Value2'.


title: HISTORY
content:
<b>busctl</b> was introduced as part of the <i>systemd</i> project, specifically with <i>systemd</i> version 217 (released in late 2014). Its development is closely tied to <i>systemd</i>'s increasing reliance on D-Bus for inter-process communication and system management. It provides a native <i>systemd</i> tool for D-Bus interaction, complementing other <i>systemd</i> utilities like <b>systemctl</b> that also extensively use D-Bus. Its inclusion streamlined D-Bus introspection, debugging, and direct interaction within the <i>systemd</i> ecosystem, offering a more integrated and user-friendly experience compared to prior standalone D-Bus utilities.


title: SYNOPSIS
content:
<i><b>bvnc</b></i> [<i>options</i>] <i>host</i>[::<i>port</i> | :<i>display</i>]<br><i><b>bvnc</b></i> [<i>options</i>] <i>connection-string</i>


title: PARAMETERS
content:
<b><i>host</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The hostname or IP address of the VNC server to connect to.<br><br><b><i>:display</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The display number of the VNC server (e.g., :1 for port 5901). Defaults to :0 if not specified.<br><br><b><i>::port</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The specific TCP port number to connect to (e.g., ::5901). Overrides the display number if both are present.<br><br><b><b>-password</b> <i>file</i> | <i>prompt</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the password for authentication. It can be read from a file or prompted interactively.<br><br><b><b>-fullscreen</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts the VNC client in fullscreen mode.<br><br><b><b>-geometry</b> <i>WxH</i>[<i>+X+Y</i>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the initial window geometry (widthxheight and optional position) for the client window.<br><br><b><b>-viewonly</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Connects in view-only mode, disabling keyboard and mouse input to the remote server.<br><br><b><b>-share</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Allows other VNC clients to connect to the same display session (if supported by the server).<br><br><b><b>-encodings</b> <i>encoding-list</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the preferred VNC encodings to use, in order of preference (e.g., 'tight,hextile,zrle').<br><br><b><b>-compresslevel</b> <i>0-9</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the compression level for the VNC connection (0 for no compression, 9 for maximum).<br><br><b><b>-quality</b> <i>0-9</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the image quality level for lossy encodings (e.g., Tight or JPEG).<br><br><b><b>-via</b> <i>gateway</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Connects to the VNC server via an SSH tunnel through a specified gateway host.<br><br>


title: DESCRIPTION
content:
The command <i><b>bvnc</b></i> is <b>not a standard or commonly recognized command</b> in most Linux distributions. It is highly likely that this name refers to a specific, niche, or custom script, or possibly a misspelling of other common VNC client commands like <i><b>vncviewer</b></i>, <i><b>xtightvncviewer</b></i>, <i><b>vinagre</b></i>, or <i><b>remmina</b></i>.<br><br>Assuming <i><b>bvnc</b></i> were a functional VNC client, its purpose would be to establish a connection to a remote VNC (Virtual Network Computing) server. VNC is a graphical desktop sharing system that allows users to remotely control another computer's desktop. A VNC client (like a hypothetical <i><b>bvnc</b></i>) receives the remote desktop's screen updates and sends local keyboard and mouse events back to the server, effectively allowing remote interaction with the graphical interface. Such a client would typically require the hostname or IP address of the VNC server and, optionally, a port number or display number, along with a password for authentication.


title: CAVEATS
content:
The primary caveat is that <i><b>bvnc</b></i> is <b>not a standard Linux command</b>. Users looking for VNC client functionality should instead use well-established commands like <i><b>vncviewer</b></i> (from various VNC packages like TightVNC, TigerVNC, RealVNC), <i><b>xtightvncviewer</b></i>, or graphical clients like <i><b>vinagre</b></i> or <i><b>remmina</b></i>.<br><br>If a custom script or application named <i><b>bvnc</b></i> exists on a specific system, its behavior, options, and security implications would depend entirely on its implementation. Standard VNC connections are often unencrypted, making them vulnerable to eavesdropping unless secured via an SSH tunnel or VPN. Always ensure connections are encrypted for sensitive data.


title: FINDING A VNC CLIENT
content:
If <i><b>bvnc</b></i> was intended as a VNC client, you can install one using your distribution's package manager. For Debian/Ubuntu, try <i><b>sudo apt install tigervnc-viewer</b></i> or <i><b>apt install xtightvncviewer</b></i>. For Fedora/RHEL, use <i><b>sudo dnf install tigervnc</b></i>. Graphical clients like <i><b>vinagre</b></i> or <i><b>remmina</b></i> are often available through desktop environment menus or direct installation.


title: SEE ALSO
content:
<i>vncviewer(1)</i>, <i>xtightvncviewer(1)</i>, <i>vinagre(1)</i>, <i>remmina(1)</i>, <i>ssvnc(1)</i>, <i>vncserver(1)</i>


title: SYNOPSIS
content:
As 'cacaclock' is a non-standard, custom command, its syntax is not universally defined. Common invocations would be:<br><br><i>cacaclock</i><br><br>If implemented as a script, it might accept basic options:<br><br><i>cacaclock</i> <b>[</b><i>options</i><b>]</b>


title: PARAMETERS
content:
<b><i>(None universally defined)</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Since 'cacaclock' is typically a custom script or program, there are no universally defined or standard parameters. Implementations vary widely; simple scripts might not accept any options, or perhaps only common ones like a help flag (e.g., <i>-h</i>, <i>--help</i>) or a version flag (e.g., <i>-v</i>, <i>--version</i>). Any specific options would depend entirely on how a particular user or developer chose to implement their version of 'cacaclock'.<br><br>


title: DESCRIPTION
content:
The command 'cacaclock' is not a standard, pre-installed Linux utility found in most distributions. Instead, it typically refers to a custom-written script or program designed to display a real-time clock directly within the terminal, utilizing character-based graphics, often referred to as 'ASCII art' or 'ANSI art'. The 'caca' prefix strongly suggests an association with the <i>libcaca</i> library, which enables applications to render graphical primitives directly to an ASCII terminal, often for humorous or artistic effect. Such a command would aim to provide a visually distinctive clock display, potentially animated, colorful, or rendered using unique character patterns, departing from the plain text output of standard commands like <i>date</i>. Its implementation can range from a simple shell script combining <i>watch</i> and <i>date</i> with text-art utilities (like <i>toilet</i>, <i>figlet</i>, or <i>cowsay</i>) to a more complex program using <i>libcaca</i> for sophisticated pixel-to-character conversions, mimicking a graphical clock. The primary purpose of 'cacaclock' is usually aesthetic appeal, entertainment, or as a fun terminal demonstration.


title: CAVEATS
content:
<b><i>Not a standard Linux command</i></b><br>'cacaclock' is not part of standard Linux distributions or common utility packages. Any instance of 'cacaclock' you encounter is highly likely to be a custom script, a personal project, or part of a niche collection of terminal art tools. This implies that its availability, specific behavior, and any potential options will vary greatly or might not exist at all on most systems unless specifically installed or created by the user.<br><br><b><i>Dependencies</i></b><br>If implemented using libraries like <i>libcaca</i> or utilities such as <i>toilet</i>, <i>figlet</i>, <i>cowsay</i>, or <i>lolcat</i>, these dependencies would need to be installed on the system for 'cacaclock' to function correctly.


title: <B><I>COMMON IMPLEMENTATIONS</I></B>
content:
Due to its custom nature, 'cacaclock' could be implemented in various ways:<br>1.  <b>Shell Script:</b> A common approach involves a simple `while true` loop combined with `clear`, `date`, and text-art utilities (like `toilet`, `figlet`, `cowsay`, or `lolcat`) piped together to create an animated, character-based clock.<br>2.  <b>C/C++ Program:</b> A more sophisticated implementation might use <i>libcaca</i> or <i>ncurses</i> directly to draw the clock, potentially incorporating animations, custom fonts, or more complex character mappings.<br>3.  <b>Scripting Languages:</b> Programs written in Python, Perl, or Ruby could leverage their respective libraries for terminal manipulation and ASCII art generation.


title: <B><I>PURPOSE AND APPEAL</I></B>
content:
The primary purpose of a 'cacaclock' is typically aesthetic and recreational. It provides a visually engaging and often humorous way to display time in a terminal environment, serving as a personal embellishment for a custom system dashboard, a screensaver alternative, or simply as a fun demonstration of what's possible with terminal graphics and ASCII art.


title: HISTORY
content:
As 'cacaclock' is not a standard or officially maintained Linux command, it does not have a documented history of development or widespread usage like many other core utilities. Its existence is likely tied to individual programming efforts, terminal art enthusiasts, or demonstration scripts within the <i>libcaca</i> community, rather than a formal project lifecycle or continuous development.


title: DESCRIPTION
content:
<b>cacafire</b> is a fascinating command-line utility that renders a dynamic, colorful fire animation directly within your terminal. It is a prime demonstration of the capabilities of <b>libcaca</b>, a graphics library that aims to output text instead of pixels.<br><br>Unlike traditional graphics libraries, <b>libcaca</b> converts graphical primitives into ASCII art, block characters, or other text-based representations, making <b>cacafire</b> a unique visual experience. The animation continuously generates a flickering flame effect, using a variety of characters and ANSI color codes to simulate heat and movement.<br><br>It's widely used for amusement, as a screensaver, or simply to showcase the graphical prowess achievable within a text-only environment. While primarily an entertainment tool, it also serves as an excellent test of a terminal emulator's color and character rendering capabilities. It runs continuously until interrupted (e.g., by <b>Ctrl+C</b>).


title: CAVEATS
content:
<i>Resource Intensive</i>: <b>cacafire</b> can be CPU-intensive, especially on older systems or when running in less optimized terminal emulators, due to its continuous rendering of complex ASCII art.<br><br><i>Color Support Required</i>: Requires a terminal emulator that supports ANSI color escape codes (VT100 compatible) to display the fire animation correctly and vibrantly. Without proper color support, the output will appear monochrome or garbled.<br><br><i>Library Dependency</i>: Relies on the <b>libcaca</b> library being installed on the system.<br><br><i>Terminal Compatibility</i>: Performance and visual quality may vary across different terminal emulators.


title: <I>CTRL+C TO EXIT</I>
content:
The <b>cacafire</b> command runs indefinitely, continuously rendering the fire animation. To stop the animation and return to the command prompt, press <b>Ctrl+C</b>. This sends an interrupt signal (SIGINT) to the process.


title: <I>AMUSEMENT AND DEMONSTRATION</I>
content:
While not a traditional utility, <b>cacafire</b> serves as a delightful example of creative programming. It's often used for fun, as a terminal background, or to impress others with the graphical capabilities of the command line interface, proving that even a text-only environment can be visually dynamic.


title: HISTORY
content:
<b>cacafire</b> is an iconic demonstration program from the <b>libcaca</b> project, initiated by Sam Hocevar. The <b>libcaca</b> library itself was conceived as a "Color ASCII Art library", designed to output graphics as character art rather than pixels. Developed to provide a cross-platform, efficient way to render graphical content in text mode, <b>cacafire</b> quickly became a beloved example of its capabilities. Its development reflects a unique niche in open-source software, pushing the boundaries of what's possible in a traditional command-line interface.


title: SYNOPSIS
content:
<b>caddy</b> <I>[command]</I> <I>[flags]</I><br><br>Common usage examples:<br><b>caddy run</b> <I>[--config <path>]</I> <I>[--adapter <name>]</I><br><b>caddy start</b> <I>[--config <path>]</I> <I>[--adapter <name>]</I><br><b>caddy stop</b><br><b>caddy reload</b> <I>[--config <path>]</I> <I>[--adapter <name>]</I><br><b>caddy validate</b> <I>[--config <path>]</I> <I>[--adapter <name>]</I>


title: PARAMETERS
content:
<b><b>--config</b> <I><path></I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the path to the Caddy configuration file (e.g., Caddyfile or JSON). If omitted, Caddy searches for a Caddyfile in standard locations.<br><br><b><b>--adapter</b> <I><name></I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Name of the config adapter to use if the config file is not JSON (e.g., 'caddyfile'). This tells Caddy how to parse the provided configuration.<br><br><b><b>--envfile</b> <I><path></I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Loads environment variables from the specified file before Caddy starts, useful for secrets or dynamic configuration.<br><br><b><b>--cpu</b> <I><percentage></I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a CPU cap for Caddy as a percentage (e.g., '75' for 75% of one CPU core). Can be specified as a floating point number.<br><br><b><b>--watch</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables automatic configuration reloading when the config file changes. Primarily for development environments, not recommended for production.<br><br><b><b>--persistence-dir</b> <I><path></I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the directory where Caddy stores persistent data, such as acquired certificates and keys, and OCSP staples.<br><br><b><b>--resume</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;If true, Caddy will attempt to resume from the last saved configuration state before applying new ones, ensuring continuity.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the Caddy version, architecture, and other build information, then exits.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints help information for the <b>caddy</b> command or a specific subcommand.<br><br>


title: DESCRIPTION
content:
Caddy is an open-source, modern web server and reverse proxy written in Go, renowned for its automatic HTTPS capabilities. Unlike traditional web servers, Caddy leverages the ACME protocol to provision and renew SSL/TLS certificates from authorities like Let's Encrypt, ensuring secure connections with minimal configuration. It natively supports HTTP/2 and HTTP/3 (QUIC), providing high performance and efficiency. Caddy's primary configuration interface, the Caddyfile, is designed for simplicity and readability, allowing users to define complex site setups with ease. Beyond serving static files, Caddy excels as a reverse proxy, load balancer, API gateway, and even a file server. Its modular architecture supports a wide range of plugins, extending its functionality for various use cases. Caddy aims to make web serving more accessible and secure by default.


title: CAVEATS
content:
While Caddy significantly simplifies web serving, it relies on external services like Let's Encrypt for automatic HTTPS, requiring public internet access and properly configured DNS for domain validation. Complex configurations might still benefit from a deeper understanding of its Caddyfile language or native JSON configuration. For production environments, Caddy should be run as a background service, typically managed by systemd or similar service managers, to ensure proper startup, shutdown, and resource management.


title: AUTOMATIC HTTPS AND ACME
content:
Caddy's signature feature is its ability to automatically obtain and renew SSL/TLS certificates for your domains using the ACME (Automatic Certificate Management Environment) protocol. It transparently interacts with Certificate Authorities like Let's Encrypt to ensure your sites are always served over HTTPS, eliminating manual certificate management and enhancing security by default.


title: THE CADDYFILE
content:
The Caddyfile is a simple, human-readable configuration language that Caddy natively understands. While Caddy's internal configuration is JSON, the Caddyfile acts as a powerful and convenient adapter, allowing users to define server blocks, routes, and directives with minimal syntax, making complex setups straightforward and accessible for beginners.


title: HISTORY
content:
Caddy was initially created by Matt Holt, with its first public release in 2015, quickly gaining traction for its groundbreaking automatic HTTPS feature, which significantly lowered the barrier to entry for securing websites. Version 1 established its reputation for simplicity and security. A major rewrite, Caddy 2, was released in 2020. This second iteration, also written in Go, introduced a more robust and modular architecture, a powerful new JSON configuration interface (with the Caddyfile acting as a popular adapter), and expanded capabilities as a general-purpose application server, API gateway, and reverse proxy. Its development continues to focus on performance, security, and ease of use.


title: PARAMETERS
content:
<b><code>-k &lt;key&gt;</code></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the integer shift key (e.g., 3 for a shift of three positions). This key determines how many positions each letter is shifted in the alphabet. If omitted, some implementations might default to a specific key (like 13 for ROT13) or prompt the user.<br><br><b><code>-d</code></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Activates decryption mode. When this option is used, the command shifts characters backward by the specified key, effectively reversing an encryption operation. If `-d` is not present, the command defaults to encryption mode (shifting characters forward).<br><br><b><code>[file...]</code></b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more input files to process. The command will read the content from these files, apply the Caesar cipher transformation, and typically print the result to standard output (<code>stdout</code>). If no files are specified, the command usually reads from standard input (<code>stdin</code>).<br><br>


title: DESCRIPTION
content:
The `caesar` command, while <I>not a standard or commonly pre-installed Linux utility</I>, conceptually implements the <B>Caesar cipher</B>. This is one of the simplest and oldest substitution ciphers, where each letter in the plaintext is replaced by a letter a fixed number of positions down or up the alphabet. For instance, with a shift of 3, 'A' would become 'D', 'B' would become 'E', and so on, wrapping around from 'Z' back to 'A'.<br><br>If available (typically as a custom script or part of a specialized package), the `caesar` command would allow users to encrypt or decrypt text by specifying a numeric shift key. It operates on alphabetic characters, usually preserving case and leaving non-alphabetic characters unchanged. Due to its simplicity and susceptibility to brute-force attacks, the Caesar cipher (and thus a `caesar` command) is unsuitable for any real-world security applications. It is primarily used for educational purposes, demonstrating basic cryptographic principles, or for simple text obfuscation like the ROT13 variant.


title: CAVEATS
content:
This command is <B>not a standard Linux utility</B> and is typically not found pre-installed on most distributions. Implementations of a `caesar` command are often custom scripts, educational programs, or part of niche packages. Its use for secure communication is strongly discouraged due to the extreme weakness of the Caesar cipher, which can be easily broken through frequency analysis or brute-force attacks. Functionality and available options may vary significantly between different custom implementations.


title: CHARACTER HANDLING
content:
Most `caesar` implementations focus solely on alphabetic characters (A-Z, a-z). Non-alphabetic characters (such as numbers, punctuation marks, spaces, and special symbols) are typically left unchanged and passed through to the output as-is. Case sensitivity is usually maintained, meaning 'A' shifted by 3 becomes 'D', and 'a' shifted by 3 becomes 'd'. The shift operation wraps around the alphabet, so 'Z' shifted by 1 becomes 'A', and 'z' shifted by 1 becomes 'a'.


title: SECURITY IMPLICATIONS
content:
It is critical to understand that the Caesar cipher offers virtually no cryptographic security. With only 25 possible unique shifts (for a 26-letter English alphabet), it can be easily broken by trying every possible key (a brute-force attack) in a matter of seconds. Additionally, it is highly vulnerable to frequency analysis, a cryptanalytic technique that exploits the uneven distribution of letter frequencies in a language. For any real security needs, modern, robust encryption algorithms and tools like OpenSSL, GnuPG, or `crypt(1)` should be used.


title: HISTORY
content:
The Caesar cipher itself dates back to ancient Rome, famously used by Julius Caesar for private correspondence. It is documented in Suetonius's 'Lives of the Twelve Caesars'. Its simplicity made it practical for manual use but also its downfall in terms of security as cryptanalysis evolved. While the cipher has a long and prominent history, a dedicated 'caesar' command-line utility for Linux is a relatively modern, often custom or educational, development. It leverages command-line interfaces to demonstrate this historical cryptographic method rather than serving as a general-purpose security tool alongside other standard utilities.


title: PARAMETERS
content:
<b><B>--help</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help information and exits.<br><br><b><B>--version</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information and exits.<br><br><b><B>--activate</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Activates Caffeine, preventing system idleness. Availability varies by implementation and is not universally supported via CLI.<br><br><b><B>--deactivate</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Deactivates Caffeine, allowing the system to idle. Availability varies by implementation and is not universally supported via CLI.<br><br><b><B>--toggle</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Toggles the Caffeine state between active and inactive. Availability varies by implementation and is not universally supported via CLI.<br><br>


title: DESCRIPTION
content:
The <I>caffeine-indicator</I> is an application designed to temporarily prevent your Linux system from becoming idle. When active, it stops actions like screen blanking, screen locking, and system suspension, making it ideal for presentations, watching videos, or running long-duration tasks without user interaction. It's typically implemented as a small icon in your desktop environment's system tray or top bar, allowing for quick toggling of its "awake" state.<br><br>While the executable often associated with this functionality is simply <I>caffeine</I>, it functions as a user-friendly frontend to underlying system mechanisms like <I>xset</I> or <I>systemd-inhibit</I>, ensuring your display remains on and your system stays active as long as needed. Its primary mode of operation is through a graphical interface, making command-line interaction limited or non-existent in many modern implementations.


title: CAVEATS
content:
The <I>caffeine-indicator</I> is primarily a graphical utility. Its command-line interface and available options can vary significantly or be entirely absent depending on the specific implementation, package, and Linux distribution. Modern versions (e.g., as a GNOME Shell Extension) often have no direct CLI interaction. It prevents idleness but does not inhibit explicit system shutdown or reboot commands.


title: GUI INTERACTION
content:
The primary and most common way to interact with Caffeine is via its graphical icon, usually found in the system tray, notification area, or top bar of your desktop environment. Clicking this icon typically toggles its active state or provides a menu for further options.


title: UNDERLYING MECHANISMS
content:
While <I>caffeine-indicator</I> provides a convenient front-end, it often works by leveraging standard Linux utilities. This includes commands like <I>xset s off</I> to disable X screen blanking, or more robustly, using <I>systemd-inhibit</I> to register a system-wide inhibition lock against suspend, idle, or screen-locking actions.


title: HISTORY
content:
The <I>caffeine-indicator</I> originated as a popular applet for Ubuntu's Unity desktop environment. It gained prominence for its simple solution to prevent screen blanking and system suspension during activities like presentations or video playback, where continuous user input isn't present. Over time, its functionality has been adapted into various forms, including GNOME Shell extensions and similar indicator applets for other desktop environments, maintaining its core purpose of keeping the system 'awake'.


title: PARAMETERS
content:
<b><b>&lt;PATH&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>The path to the new project directory. The last component of the path will be used as the project name, unless overridden by `<b>--name</b>`. For example, `cargo new my_app` creates `my_app/`, while `cargo new projects/my_app` creates `projects/my_app/`.</i><br><br><b><b>--bin</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Creates a binary application project (this is the default behavior). This sets up `src/main.rs`.</i><br><br><b><b>--lib</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Creates a library project instead of a binary. This sets up `src/lib.rs`.</i><br><br><b><b>--vcs &lt;VCS&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Initializes a new repository for the specified Version Control System. Common values are `git` (default), `hg` (Mercurial), or `none` to skip VCS initialization.</i><br><br><b><b>--edition &lt;YEAR&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Specifies the Rust edition to use for the new project (e.g., `2018`, `2021`). Defaults to the latest stable edition.</i><br><br><b><b>--name &lt;NAME&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Sets the package name in `Cargo.toml`, which can be different from the directory name. Useful if the new directory's name is not the desired package name.</i><br><br><b><b>--registry &lt;REGISTRY&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Specifies the registry to use when publishing this package.</i><br><br><b><b>--offline</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Run without accessing the network.</i><br><br><b><b>-h, --help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Prints help information for the `cargo new` command.</i><br><br><b><b>-v, --verbose</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Use verbose output.</i><br><br><b><b>-q, --quiet</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Do not print Cargo log messages.</i><br><br>


title: DESCRIPTION
content:
<i><b>cargo new</b> is a fundamental command within the Rust programming language's package manager and build system, Cargo. It is used to quickly scaffold a new Rust project, setting up the essential directory structure and initial files required for development. When executed, <b>cargo new</b> creates a new directory at the specified path, containing a <b>Cargo.toml</b> file (the project manifest) and a <b>src</b> directory. Inside <b>src</b>, it generates either a <b>main.rs</b> file (for a binary application, the default) or a <b>lib.rs</b> file (for a library). This command streamlines the initial setup process, allowing developers to immediately start writing Rust code without manually configuring the project layout or build system. It also initializes a Git repository by default, facilitating version control from the outset.</i>


title: CAVEATS
content:
<i><br><b>1. Rust Toolchain Required:</b> `cargo new` relies on the Rust toolchain (including Cargo) being properly installed on your system, typically via Rustup.<br><b>2. Directory Creation:</b> The command creates a new directory for the project. If a directory with the specified name already exists at the given path and is not empty, `cargo new` will typically fail to prevent accidental data loss.<br><b>3. Default Behaviors:</b> By default, `cargo new` creates a binary application project and initializes a Git repository. To create a library or use a different VCS (or none), explicit options (`<b>--lib</b>`, `<b>--vcs</b>`) must be provided.</i>


title: <B>PROJECT STRUCTURE</B>
content:
<i>Upon execution, `cargo new my_project` typically creates the following directory and file structure:<br><br>`my_project/`<br>&nbsp;&nbsp;&nbsp;&nbsp;`Cargo.toml`<br>&nbsp;&nbsp;&nbsp;&nbsp;`src/`<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;`main.rs` (for `--bin` or default)<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;`lib.rs` (for `--lib`)<br>&nbsp;&nbsp;&nbsp;&nbsp;`.git/` (if `--vcs git` or default VCS is active)</i>


title: <B><CODE>CARGO.TOML</CODE> MANIFEST</B>
content:
<i>This file is the manifest for your Rust project. It contains essential metadata about the package (e.g., `name`, `version`, `authors`, `edition`) and specifies dependencies (e.g., `[dependencies]`). `cargo new` generates a basic `Cargo.toml` to get you started, which is crucial for Cargo to understand and build your project.</i>


title: <B>INITIAL CODE</B>
content:
<i>For a binary project (default), `main.rs` typically contains a simple "Hello, world!" program, making it runnable immediately (`cargo run`). For a library, `lib.rs` will contain a basic testable function, demonstrating how to define and use a library crate.</i>


title: HISTORY
content:
<i>The `cargo new` command has been a core part of the Rust ecosystem since the early days of Cargo's development. Cargo itself was designed to manage Rust projects efficiently, and `cargo new` was fundamental to providing a standardized and easy way to bootstrap new projects. It has evolved alongside the Rust language, incorporating features like Rust Editions and improving project structure conventions, always aiming to simplify the developer's initial setup experience and streamline the development workflow.</i>


title: SEE ALSO
content:
cargo(1): <i>The Rust package manager and build tool.</i>, cargo build(1): <i>Compile the current package.</i>, cargo run(1): <i>Build and execute the current package.</i>, cargo check(1): <i>Check the current package for errors.</i>, cargo init(1): <i>Create a new Cargo package in an existing directory.</i>


title: PARAMETERS
content:
<b><b>--bin</b> <I>NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Run the specified binary. Use this when your package has multiple binary targets defined in <i>Cargo.toml</i>.<br><br><b><b>--example</b> <I>NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Run the specified example. Use this when your package has example targets defined in <i>Cargo.toml</i>.<br><br><b><b>--package</b> <I>SPEC</I>, <b>-p</b> <I>SPEC</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Run a binary or example from the specified package. This is useful in a workspace to specify which package to run.<br><br><b><b>--release</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Compile and run the optimized release build (located in <i>target/release/</i>), rather than the default debug build (in <i>target/debug/</i>).<br><br><b><b>--target</b> <I>TRIPLE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Build for the specified target triple (e.g., <i>x86_64-unknown-linux-gnu</i>).<br><br><b><b>--features</b> <I>FEATURES</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Space or comma separated list of features to activate for compilation.<br><br><b><b>--all-features</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Activate all available features of the current package.<br><br><b><b>--no-default-features</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not activate the <i>default</i> feature of the current package.<br><br><b><b>--jobs</b> <I>N</I>, <b>-j</b> <I>N</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Number of parallel jobs to run for compilation.<br><br><b><b>--verbose</b>, <b>-v</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Use verbose output, showing more details like executed commands.<br><br><b><b>--quiet</b>, <b>-q</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not print Cargo log messages, only program output and errors.<br><br><b><b>--manifest-path</b> <I>PATH</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Path to the <i>Cargo.toml</i> file for the package being run.<br><br><b><b>--color</b> <I>WHEN</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Control when coloring is used in the output. Options include <i>always</i>, <i>auto</i>, <i>never</i>.<br><br>


title: DESCRIPTION
content:
<i>cargo run</i> is a convenient command provided by <I>Cargo</I>, Rust's build system and package manager. It streamlines the development workflow by performing two primary actions: <br>1. It first <B>compiles</B> the current package (or a specific binary, example, or test as specified by options) into an executable.<br>2. Upon successful compilation, it then <B>executes</B> the generated binary. <br><br>This command is particularly useful during rapid development cycles, allowing developers to quickly test changes without manually compiling and then invoking the executable. It automatically handles dependency resolution and compilation, only rebuilding what's necessary based on source file changes. If multiple runnable targets (like multiple binaries or examples) are found within a package and none is specified via options, <i>cargo run</i> will typically prompt the user to choose or fail with an ambiguity error.


title: CAVEATS
content:
When using <i>cargo run</i>, it's crucial to understand the <B>--</B> separator. Any arguments appearing after <B>--</B> are passed directly to the <I>executed program</I>, not to <i>cargo run</i> itself. For example, <i>cargo run -- --some-arg value</i> passes <i>--some-arg value</i> to your Rust binary. <br>If multiple binary or example targets are defined in your <i>Cargo.toml</i> and you do not specify which one to run (e.g., with <i>--bin</i> or <i>--example</i>), <i>cargo run</i> might display an error or prompt you to select one, leading to potential ambiguity in automated scripts.


title: PASSING ARGUMENTS TO YOUR PROGRAM
content:
To pass arguments to the compiled executable, you must use <B>--</B> as a separator between <i>cargo run</i>'s options and your program's arguments. <br><i>Example: cargo run -- --input data.txt --verbose</i> <br>Here, <i>--input data.txt --verbose</i> will be received by your Rust program.


title: TARGET SELECTION AND AMBIGUITY
content:
If your <i>Cargo.toml</i> defines multiple binaries (e.g., <i>src/bin/my_app.rs</i> and <i>src/bin/another_app.rs</i>) or examples, <i>cargo run</i> will require you to explicitly choose which one to run using <i>--bin <NAME></i> or <i>--example <NAME></i> respectively. If only one binary is defined (typically <i>src/main.rs</i>), <i>cargo run</i> will execute it by default.


title: HISTORY
content:
<i>cargo run</i> has been a fundamental command within the Cargo build system since its inception, predating the stable release of Rust 1.0. Its purpose has consistently been to provide a seamless 'build and execute' cycle, drastically improving developer productivity by abstracting away the manual compilation steps. While new options have been added over time to support features like workspaces, profiles, and more granular target selection, the core functionality and user experience of <i>cargo run</i> have remained remarkably consistent, establishing it as a go-to command for everyday Rust development.


title: PARAMETERS
content:
<b><I>command</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The executable program to be run under <b>catchsegv</b>'s supervision.<br><br><b>[<I>arguments</I>...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Any command-line arguments to pass to the specified <I>command</I>.<br><br>


title: DESCRIPTION
content:
<b>catchsegv</b> is a utility provided by the GNU C Library (glibc) development packages. Its primary purpose is to help diagnose segmentation faults (<I>SIGSEGV</I>) by intercepting them and printing a symbolic backtrace of the program's execution stack at the time of the fault. Instead of the program simply crashing, <b>catchsegv</b> preloads a special shared library, <I>libSegFault.so</I>, into the target application's address space. This library installs a signal handler for <I>SIGSEGV</I>. When a segmentation fault occurs, this handler is invoked, and it attempts to print a meaningful backtrace, often including function names and line numbers if the program was compiled with debugging symbols. This makes it a quick and convenient tool for developers to get initial insights into where and why a program crashed due to memory access errors, without needing to attach a full-fledged debugger like GDB immediately. It's particularly useful for non-interactive debugging or for quickly identifying the crash location in command-line tools.


title: CAVEATS
content:
<b>catchsegv</b> is not a full debugger; it only provides a backtrace and does not allow interactive inspection, memory modification, or stepping through code.<br>It typically requires the installation of <I>glibc</I> development packages to provide <I>libSegFault.so</I>.<br>It only works with dynamically linked executables, as its mechanism relies on the dynamic linker (<I>LD_PRELOAD</I>).<br>The quality and detail of the backtrace (e.g., function names, line numbers) depend on whether the target program was compiled with debugging symbols (e.g., with <I>-g</I> flag). Without them, only memory addresses will be shown.<br>While typically minimal, preloading a library can introduce a slight overhead or alter program behavior in subtle ways.


title: HOW IT WORKS
content:
Under the hood, <b>catchsegv</b> is typically a shell script wrapper. It sets the <I>LD_PRELOAD</I> environment variable to point to the <I>libSegFault.so</I> shared library (e.g., <I>LD_PRELOAD=/usr/lib/libSegFault.so</I>) before executing the specified command. This instructs the dynamic linker to load <I>libSegFault.so</I> into the process's memory space before any other libraries. <I>libSegFault.so</I> then installs a signal handler for <I>SIGSEGV</I> that, upon detection of a segmentation fault, generates and prints a symbolic backtrace to <I>stderr</I>.


title: CONFIGURING <I>LIBSEGFAULT.SO</I> VIA ENVIRONMENT VARIABLES
content:
The behavior of the preloaded <I>libSegFault.so</I> can be influenced by several environment variables, though these are not direct <b>catchsegv</b> parameters:<br><I>SEGFAULT_OUTPUT_METHOD</I>: Specifies where the backtrace output should go (e.g., <I>STDOUT</I>, <I>STDERR</I>, <I>FILE=&lt;path&gt;</I>, <I>PIPE=&lt;command&gt;</I>). Default is usually <I>STDERR</I>.<br><I>SEGFAULT_SIGNAMES</I>: Set to <I>1</I> to include signal names in the backtrace output.<br><I>SEGFAULT_USE_ALTSTACK</I>: Set to <I>1</I> to use an alternative signal stack, which can be useful in cases where the stack might be corrupted.


title: HISTORY
content:
<b>catchsegv</b> and its underlying shared library, <I>libSegFault.so</I>, are long-standing utilities within the GNU C Library (<I>glibc</I>) ecosystem. They were developed as part of <I>glibc</I>'s debugging and diagnostic features to provide developers with a quick way to get actionable information from segmentation faults without requiring a full debugger session. Its exact introduction date into mainline <I>glibc</I> is not widely publicized, but it has been a standard part of <I>glibc</I> development tools for many years, evolving with the library itself.


title: SYNOPSIS
content:
<b>certutil</b> [<I>global-options</I>] <I>command</I> [<I>command-options</I>] [<I>arguments</I>]<br><br>Examples:<br><b>certutil</b> <b>-L</b> <b>-d</b> <I>/path/to/nssdb</I><br><b>certutil</b> <b>-A</b> <b>-n</b> "My Cert" <b>-t</b> "C,," <b>-d</b> <I>/path/to/nssdb</I> <b>-i</b> <I>cert.pem</I>


title: PARAMETERS
content:
<b><b>-d</b> <I>&lt;database_directory&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the directory containing the NSS certificate and key database files. Common paths include <i>~/.pki/nssdb</i> or <i>/etc/pki/nssdb</i>.<br><br><b><b>-P</b> <I>&lt;database_prefix&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the database type prefix, typically <i>sql:</i> for SQLite-based NSS databases.<br><br><b><b>-N</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prompts to set a new password for the NSS database, or change an existing one.<br><br><b><b>-W</b> <I>&lt;password&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the password for the NSS database directly on the command line. Use with caution as it can expose the password in shell history.<br><br><b><b>-L</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>List Certificates:</I> Displays certificates and their trust attributes stored in the specified NSS database.<br><br><b><b>-A</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Add Certificate:</I> Adds a new certificate to the database. Often used with <b>-n</b> (nickname), <b>-t</b> (trust attributes), and <b>-i</b> (input file).<br><br><b><b>-D</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Delete Certificate:</I> Removes a certificate from the database. Requires the certificate's nickname via <b>-n</b>.<br><br><b><b>-S</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Generate Key Pair / CSR:</I> Generates a new RSA or ECC key pair and optionally a Certificate Signing Request (CSR).<br><br><b><b>-V</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Verify Certificate:</I> Verifies the validity, signature, and trust chain of a certificate. Can operate on certificates in the database (with <b>-n</b>) or from a file (with <b>-i</b>).<br><br><b><b>-M</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Modify Trust Attributes:</I> Changes the trust attributes of an existing certificate in the database. Requires <b>-n</b> and <b>-t</b>.<br><br><b><b>-E</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Export Certificate/Key:</I> Exports a certificate, key, or entire PKCS#12 bundle from the database to a file.<br><br><b><b>-I</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Import Certificate/Key:</I> Imports a certificate or key into the database from a file.<br><br><b><b>-K</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>List Keys:</I> Displays private keys stored in the database, along with their associated nicknames.<br><br>


title: DESCRIPTION
content:
<i>certutil</i> is a command-line utility provided by the Network Security Services (NSS) cryptographic library. On Linux, it's typically found within the <i>nss-tools</i> package. Its primary purpose is to manage certificates, key pairs, and Certificate Revocation Lists (CRLs) stored in NSS databases. These databases are often used by applications like web browsers (e.g., Firefox), email clients, and servers (e.g., Apache with <i>mod_nss</i>) to store cryptographic objects.<br><br><i>certutil</i> allows users to perform various operations, including listing, adding, deleting, and modifying certificates, generating new key pairs and certificate requests (CSRs), verifying certificate chains, managing trust settings, and importing/exporting cryptographic objects in various formats (e.g., PEM, DER, PKCS#12). It's a powerful tool for administrators and developers working with Public Key Infrastructure (PKI) and secure communications based on NSS.


title: CAVEATS
content:
<b>Complexity:</b> <i>certutil</i> has a large number of options and subcommands, making it complex to master. Refer to the manual page for comprehensive usage.<br><b>NSS Database Specific:</b> It primarily manages NSS databases, not generic system-wide certificate stores (like those used by OpenSSL).<br><b>Password Security:</b> Directly providing passwords on the command line using <b>-W</b> is insecure as it can be stored in shell history or visible in process listings.<br><b>Package Dependency:</b> On Linux, <i>certutil</i> is typically provided by the <i>nss-tools</i> or a similar package and may not be installed by default.


title: NSS DATABASE LOCATIONS
content:
NSS databases are typically stored in specific directories. For user-specific applications like Firefox, they might be in <i>~/.pki/nssdb</i> or within the application's profile directory (e.g., <i>~/.mozilla/firefox/&lt;profile&gt;/</i>). System-wide NSS databases might be found in locations like <i>/etc/pki/nssdb</i>, depending on the distribution and configuration.


title: CERTIFICATE TRUST ATTRIBUTES (-T)
content:
When adding or modifying certificates, the <b>-t</b> option specifies trust attributes. It's a string of three characters, each representing trust for SSL client, SSL server, and email. The order is SSL-client, SSL-server, email. Common attributes include:<br><b>C,C,C</b>: Trust for SSL client, SSL server, and email (Certificate Authority for all uses).<br><b>C,C,T</b>: Trust for SSL client and SSL server, and trusted for email signing.<br><b>,,C</b>: Trusted for email signing only (not for client/server authentication).<br><b>p,p,p</b>: Default trust (e.g., for self-signed certificates, if policy permits).


title: HISTORY
content:
<i>certutil</i> is an integral part of the Network Security Services (NSS) cryptographic library, which was originally developed by Netscape Communications Corporation. NSS was made open source in 1999, becoming a foundational component for various open-source projects, most notably Mozilla Firefox and other Mozilla-based applications. Its development has been continuous under the NSS project, adapting to evolving cryptographic standards and security requirements. On Linux, it's typically distributed as part of the <i>nss-tools</i> package, making it available for system administrators and developers managing NSS-based certificate stores.


title: SYNOPSIS
content:
<b>cfssl</b> [<i>global options</i>] <i>command</i> [<i>command options</i>] [<i>arguments...</i>]<br><br>Examples:<br><b>cfssl</b> <b>gencert</b> -initca config.json | <b>cfssljson</b> -bare ca<br><b>cfssl</b> <b>sign</b> -ca ca.pem -ca-key ca-key.pem server.csr | <b>cfssljson</b> -bare server


title: PARAMETERS
content:
<b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the help message for the command or subcommand, detailing available options and usage.<br><br><b>-v, --version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the <i>cfssl</i> version information, including the release number and build details.<br><br>


title: DESCRIPTION
content:
<i>cfssl</i> is a comprehensive command-line tool and Go library developed by CloudFlare for managing Public Key Infrastructure (PKI) and TLS certificates. It simplifies various certificate operations, including generating private keys, creating Certificate Signing Requests (CSRs), issuing and signing certificates, and bundling certificates with their intermediate and root CAs. It also supports functions like generating Certificate Revocation Lists (CRLs), serving as a local or remote Certificate Authority (CA), and providing certificate information. Designed for automation and ease of use, <i>cfssl</i> offers a more streamlined approach to PKI compared to traditional tools like <i>openssl</i>, especially beneficial for large-scale deployments and automated certificate lifecycle management.


title: CAVEATS
content:
Managing private keys and certificate authority configurations with <i>cfssl</i> requires extreme care and adherence to security best practices. Misconfiguration can lead to security vulnerabilities or invalid certificates. Many operations depend on specific JSON configuration files, which require understanding their structure and schema. While simplifying common tasks, <i>cfssl</i> can still be complex for beginners due to its subcommand-based architecture and extensive options for each command.


title: SUBCOMMAND STRUCTURE
content:
<i>cfssl</i> primarily operates through a subcommand-based interface. Each major function (e.g., generating certificates, signing requests, bundling, serving as a CA) is encapsulated within a specific subcommand (e.g., <b>gencert</b>, <b>sign</b>, <b>bundle</b>, <b>serve</b>). Users should consult the help for individual subcommands (e.g., <b>cfssl gencert -h</b>) to understand their specific options and arguments, as most of <i>cfssl</i>'s functionality resides within these subcommands rather than global options.


title: JSON CONFIGURATION FILES
content:
Many advanced operations and policy definitions within <i>cfssl</i>, such as certificate profiles, CA configurations, and signing policies, are specified using JSON configuration files. This allows for highly customizable and automatable workflows, but requires familiarity with the expected JSON schemas for each command to define certificate properties, extensions, and validity periods effectively.


title: HISTORY
content:
<i>cfssl</i> was developed by CloudFlare to provide a modern, efficient, and robust toolkit for managing TLS certificates and PKI, addressing challenges encountered with traditional tools like <i>openssl</i> in large-scale, automated environments. Written in Go, it was open-sourced to contribute to the broader security community, promoting simpler and more secure certificate management practices. Its development focused on API-driven certificate services and automation.


title: SYNOPSIS
content:
The most common way to directly execute a command within a specified cgroup <br>using the <b>libcgroup-tools</b> is via <b>cgexec</b>:<br><b>cgexec</b> [<i>options</i>] <i>group_path</i> <i>command</i> [<i>arguments...</i>]


title: PARAMETERS
content:
<b><i>group_path</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The path to the cgroup directory where the command will be executed (e.g., <b>cpu:/user.slice/mygroup</b>).<br><br><b><i>command</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The executable command to run within the specified cgroup.<br><br><b><i>arguments...</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Any arguments to be passed to the <i>command</i>.<br><br><b><b>-g</b> <i>&lt;controllers:path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;(<b>cgexec</b>/<b>cgclassify</b>) Specify the cgroup(s) for the process. <br>Multiple controllers and paths can be specified (e.g., <b>cpu,memory:/mygroup</b>).<br><br><b><b>-l</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;(<b>cgget</b>/<b>cgset</b>) List parameters or cgroups.<br><br><b><b>--sticky</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;(<b>cgexec</b>) Keep the process in the cgroup even if it forks or execs, <br>ensuring all its children inherit the cgroup assignment.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display help information for the specific command.<br><br>


title: DESCRIPTION
content:
<i>cgroups</i> (control groups) is a powerful <br>Linux kernel feature that organizes processes hierarchically <br>into groups for resource management. It allows administrators to <br>distribute, account for, and isolate system resources such as CPU, <br>memory, network I/O, and block I/O among groups of processes. <br>This enables finer control over resource allocation, ensuring <br>that no single application or user can monopolize system resources <br>and impact overall system stability or performance.<br><br>It's important to note that 'cgroups' is not a single command <br>in itself, but rather a kernel mechanism. User-space interaction <br>with cgroups is primarily achieved through:<br><b>1. libcgroup-tools:</b> A suite of commands like <b>cgcreate</b>, <br><b>cgexec</b>, <b>cgclassify</b>, <b>cgget</b>, and <b>cgset</b>, <br>which allow direct manipulation of cgroup hierarchies and <br>assignment of processes.<br><b>2. systemd:</b> On modern Linux distributions, <b>systemd</b> <br>integrates deeply with cgroups, managing services and user sessions <br>within cgroup hierarchies (e.g., via <b>.slice</b>, <b>.scope</b>, and <br><b>.service</b> units). This is often the preferred method <br>for system-wide cgroup management.<br><b>3. cgroupfs:</b> Direct interaction with the <b>/sys/fs/cgroup</b> <br>pseudo-filesystem, which exposes the cgroup hierarchy and <br>control files.


title: CAVEATS
content:
<b>1. Kernel Feature, Not a Single Command:</b> 'cgroups' refers to <br>a kernel mechanism, not a single executable. Interaction is through <br>a suite of tools or <b>systemd</b>.<br><b>2. Requires Root Privileges:</b> Most cgroup operations, especially <br>creating or modifying cgroups, require root privileges.<br><b>3. Cgroupfs Mount:</b> The <b>cgroupfs</b> pseudo-filesystem must be <br>mounted (typically at <b>/sys/fs/cgroup</b>) for cgroup operations.<br><b>4. Cgroup v1 vs. v2:</b> Linux kernels support two versions of cgroups. <br>v1 allows individual controllers to be mounted separately, while v2 <br>provides a unified hierarchy. Tools and behaviors can differ.<br><b>5. systemd Integration:</b> On modern systems, <b>systemd</b> largely <br>manages cgroups, sometimes making direct use of <b>libcgroup-tools</b> <br>less common or even conflicting if not handled carefully.


title: CGROUP SUBSYSTEMS
content:
Cgroups use various 'subsystems' (or controllers) to manage <br>different types of resources. Common subsystems include:<br><b>cpu:</b> Controls CPU access.<br><b>memory:</b> Limits memory usage.<br><b>blkio:</b> Controls block I/O access.<br><b>cpuset:</b> Assigns processes to specific CPUs and memory nodes.<br><b>net_cls:</b> Tags network packets for QoS.<br><b>pids:</b> Limits the number of processes/threads a cgroup can create.<br><b>freezer:</b> Suspends or resumes processes within a cgroup.


title: CGROUP HIERARCHY
content:
Cgroups are organized in a tree-like hierarchy. <br>A child cgroup can further subdivide the resources allocated to <br>its parent. This allows for granular resource control, <br>for example, dedicating a percentage of CPU to a user, and then <br>subdividing that percentage among their running applications.


title: CGROUP V1 VS. V2
content:
<b>Cgroup v1:</b> Allows different controllers to be mounted <br>on separate hierarchies. This can lead to complexities and <br>inconsistencies when managing multiple resources.<br><b>Cgroup v2:</b> Introduces a unified hierarchy where all <br>controllers are managed within a single, consistent tree structure. <br>It aims to simplify management and provide better resource isolation <br>and fairness. Modern Linux distributions are moving towards v2.


title: HISTORY
content:
The cgroups feature was initially developed by Google engineers <br>Paul Menage and Rohit Seth, and was first merged into the Linux kernel <br>in version 2.6.24 in January 2008. It was originally named 'process containers' <br>but was later renamed to 'control groups' (cgroups) to avoid confusion <br>with other containerization technologies. <br><br>Initially, cgroups v1 was developed with individual hierarchies for each <br>subsystem. Due to design limitations and complexities, a major redesign <br>resulted in cgroups v2, which began merging into the kernel around version 3.10 <br>and became the default in many recent distributions. <br>The user-space <b>libcgroup-tools</b> package provides the command-line utilities <br>to interact with this kernel feature.


title: SEE ALSO
content:
cgroup(7), cgcreate(1), cgexec(1), cgclassify(1), cgget(1), cgset(1), lscgroup(1), lssubsys(1), systemd.resource-control(5), systemd-cgls(1)


title: SYNOPSIS
content:
<b>chacl</b> [<i>options</i>] <i>file</i>...<br><br><i>Note: As <b>chacl</b> is deprecated and functionally equivalent to <b>setfacl</b>, its synopsis mirrors that of <b>setfacl</b>.</i>


title: PARAMETERS
content:
<b><b>-m</b> <i>acl_entries</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Modify the ACL of files. This option is used to add or modify ACL entries.<br><br><b><b>-x</b> <i>acl_entries</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Remove specified ACL entries from files.<br><br><b><b>-b</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Remove all extended ACL entries. Only base ACL entries (owner, group, others) remain.<br><br><b><b>-k</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Remove the default ACL from directories.<br><br><b><b>-d</b> <i>acl_entries</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set default ACL entries for directories. New files/directories created within will inherit these.<br><br><b><b>-R</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Recursively apply operations to directories and their contents.<br><br><b><b>--restore</b> <i>file</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Restore an ACL backup from a file, typically created by <b>getfacl --omit-header</b>.<br><br><b><b>--test</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Test mode: show what would be done, but do not make any changes.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display the version information.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display help message.<br><br>


title: DESCRIPTION
content:
<b>chacl</b> is a command in Linux used to manipulate Access Control Lists (ACLs) on files and directories. ACLs provide a more granular permission system than the traditional Unix owner, group, and others permissions, allowing specific users or groups to be granted read, write, or execute permissions on a file, overriding the default permission model.<br><br>Historically, <b>chacl</b> was used for this purpose. However, on modern Linux systems, <b>chacl</b> is considered <b>deprecated</b>. It is typically provided for backward compatibility and acts as a symbolic link or a wrapper that is functionally equivalent to the <b>setfacl(1)</b> command. Therefore, while <b>chacl</b> might still exist on your system, the recommended and actively maintained tool for managing ACLs is <b>setfacl</b>. Users should migrate to using <b>setfacl</b> for all ACL manipulation tasks.


title: CAVEATS
content:
The primary caveat for <b>chacl</b> is its <b>deprecation</b>. It is no longer actively developed and maintained as a standalone tool. Modern Linux distributions provide <b>setfacl</b> as the preferred and more robust command for managing Access Control Lists. Relying on <b>chacl</b> might lead to unexpected behavior or lack of desired functionality on newer systems where it simply acts as a compatibility layer.


title: WHY USE <B>SETFACL</B> INSTEAD?
content:
<b>setfacl</b> is the officially recommended command for managing ACLs on Linux systems. It is actively maintained, offers a richer set of features, and provides consistent behavior across distributions. Using <b>setfacl</b> ensures compatibility with current ACL standards and best practices, unlike <b>chacl</b> which is a legacy command.


title: CHECKING ACL SUPPORT
content:
Before using ACL commands, ensure that the filesystem is mounted with ACL support. This is typically done by default for common filesystems like ext4, xfs, and btrfs. You can check mount options using <b>mount</b> or <b>cat /proc/mounts</b> and looking for the 'acl' option.


title: HISTORY
content:
The concept of Access Control Lists has been part of Unix-like systems for a long time, providing finer-grained control over file permissions than the traditional UID/GID/others model. <b>chacl</b> was one of the early commands designed to interact with these ACLs. As the Linux kernel's ACL implementation matured and standardized, the <b>acl</b> package emerged, introducing <b>setfacl</b> and <b>getfacl</b> as the primary utilities. Over time, <b>setfacl</b> became the more comprehensive and standardized tool. Consequently, <b>chacl</b> was marked as deprecated and largely superseded by <b>setfacl</b>, maintained primarily for backward compatibility for older scripts or muscle memory.


title: PARAMETERS
content:
<b><b>-f</b>, <b>--format</b> <I>NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the output format and color mode (e.g., <i>24bit</i>, <i>256</i>, <i>ansi</i>, <i>sixels</i>). Auto-detected if not specified.<br><br><b><b>-s</b>, <b>--size</b> <I>COLUMNSxROWS</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the exact output size in characters. Aspect ratio is maintained unless explicitly overridden.<br><br><b><b>-w</b>, <b>--width</b> <I>COLUMNS</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the maximum output width in characters, maintaining the image's aspect ratio.<br><br><b><b>-H</b>, <b>--height</b> <I>ROWS</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the maximum output height in characters, maintaining the image's aspect ratio.<br><br><b><b>-c</b>, <b>--colors</b> <I>MODE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces a specific color mode (e.g., <i>1</i> for monochrome, <i>16</i>, <i>256</i>, <i>24bit</i>). This overrides auto-detection.<br><br><b><b>-d</b>, <b>--dither</b> <I>METHOD</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Selects the dithering algorithm to use (e.g., <i>auto</i>, <i>none</i>, <i>floyd-steinberg</i>, <i>ordered</i>, <i>random</i>).<br><br><b><b>-C</b>, <b>--charset</b> <I>NAME</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Chooses the character set to render the image (e.g., <i>auto</i>, <i>full</i>, <i>symbols</i>, <i>half-block</i>, <i>block</i>, <i>ascii</i>, <i>braille</i>).<br><br><b><b>-o</b>, <b>--output</b> <I>FILE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Writes the character art output to a specified file instead of standard output.<br><br><b><b>--center</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Centers the output horizontally within the current terminal width.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information for <b>chafa</b> and exits.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a comprehensive help message with all options and exits.<br><br>


title: DESCRIPTION
content:
<b>chafa</b> is a powerful command-line utility designed to transform graphical images into highly detailed character art, suitable for display in a terminal. It supports a wide array of output modes, including true color (24-bit), 256-color, 16-color, ANSI, and monochrome, making it versatile for various terminal environments. Beyond basic ASCII art, <b>chafa</b> can leverage advanced Unicode characters (like block elements and braille characters) to achieve impressive fidelity.<br><br>The tool intelligently handles image scaling, aspect ratio correction, and employs sophisticated dithering algorithms to optimize visual quality even when constrained by limited character sets or color palettes. It supports numerous image formats such as PNG, JPEG, GIF, BMP, TIFF, and WebP, and can even handle animated GIFs. <b>chafa</b> automatically detects terminal capabilities for optimal output but allows manual override for precise control, making it an excellent choice for displaying images in scripts, customizing terminal prompts, or simply enjoying images in a text-based environment.


title: CAVEATS
content:
The visual quality of <b>chafa</b>'s output is highly dependent on the terminal emulator, its font, and line spacing. Not all terminals fully support true color, complex Unicode characters, or advanced image protocols like Sixel or Kitty. Using large images or complex dither methods can be computationally intensive, potentially affecting performance.


title: INPUT FROM STANDARD INPUT
content:
If no <i>FILE</i> is specified, or if <i>FILE</i> is given as a single hyphen (<b>-</b>), <b>chafa</b> will read image data from standard input, allowing it to be easily piped with other commands.


title: COMMON USE CASES
content:
<b>chafa</b> is frequently used for displaying images directly within a terminal window, creating custom `motd` (Message Of The Day) files, enhancing scripts with visual output, or integrating images into terminal-based information tools like <i>neofetch</i>.


title: HISTORY
content:
<b>chafa</b> is a relatively modern tool, first released around 2017-2018, developed by Hans Petter Jansson (hpj). It emerged as a more sophisticated alternative to older text-art converters, leveraging contemporary terminal capabilities such as true color and a broader range of Unicode characters. Its development has been active, focusing on high-quality output, performance, and flexibility, quickly establishing it as a popular choice for terminal image rendering.


title: SYNOPSIS
content:
chage [<i>options</i>] <i>LOGIN</i><br><br>Common options:<br>chage [-l | -d <i>LAST_DAY</i> | -E <i>EXPIRE_DATE</i> | -I <i>INACTIVE</i> | -m <i>MIN_DAYS</i> | -M <i>MAX_DAYS</i> | -W <i>WARN_DAYS</i>] <i>LOGIN</i>


title: PARAMETERS
content:
<b>-l, --list</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display the current password aging information for the specified <i>LOGIN</i>. This is often the only option available to non-root users for their own account.<br><br><b>-d, --lastday <i>LAST_DAY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the date of the last password change to <i>LAST_DAY</i>. This can be specified as a date in YYYY-MM-DD format or as the number of days since January 1, 1970.<br><br><b>-E, --expiredate <i>EXPIRE_DATE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the date when the user's account will expire. After this date, the user will not be able to log in. <i>EXPIRE_DATE</i> can be in YYYY-MM-DD format or as days since epoch. A value of -1 will disable account expiration.<br><br><b>-I, --inactive <i>INACTIVE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the number of days after a password expires until the account is locked. If the user does not change their password within the specified <i>INACTIVE</i> days after it expires, the account becomes unusable. A value of -1 disables this feature.<br><br><b>-m, --mindays <i>MIN_DAYS</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the minimum number of days required between password changes. A user cannot change their password again until <i>MIN_DAYS</i> have passed since the last change. A value of 0 allows immediate password changes.<br><br><b>-M, --maxdays <i>MAX_DAYS</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the maximum number of days a password remains valid. After <i>MAX_DAYS</i>, the user will be forced to change their password upon next login. A value of -1 disables password expiration.<br><br><b>-W, --warndays <i>WARN_DAYS</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the number of days before a password expires that a user will receive a warning message upon login. A value of 0 means no warning will be issued.<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a help message and exit.<br><br><b>-R, --root <i>CHROOT_DIR</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Apply changes in the specified chroot directory. This is useful for managing accounts in a different root environment.<br><br>


title: DESCRIPTION
content:
The <b>chage</b> command is used by system administrators to alter user password aging information on a Linux system. This includes controlling how often a user must change their password, when their password expires, how many days their account remains active after a password expires, and how many days before expiration a user is warned. By managing these parameters, administrators can enforce security policies that require regular password changes, thereby reducing the risk of unauthorized access due to compromised or stale passwords. It directly modifies entries in the <i>/etc/shadow</i> file. The command is part of the shadow-utils package, which provides tools for managing user accounts and password security.


title: CAVEATS
content:
Root privileges are generally required to modify another user's password aging information. A regular user can typically only view their own settings using <b>chage -l</b>.<br>Incorrect use of <b>chage</b> can inadvertently lock users out of their accounts or weaken security by setting lax password policies.<br>The account expiration date (set with <b>-E</b>) refers to the account itself, not just the password. Once expired, the user cannot log in.


title: CONFIGURATION FILES
content:
<b>chage</b> primarily interacts with two system files:<br><i>/etc/shadow</i>: This file stores encrypted passwords and all password aging information for user accounts. <b>chage</b> directly modifies entries in this file.<br><i>/etc/login.defs</i>: This file contains system-wide default values for password aging parameters (e.g., PASS_MAX_DAYS, PASS_MIN_DAYS) that are applied when a new user is created. <b>chage</b> allows administrators to override these defaults for individual users.


title: HISTORY
content:
The <b>chage</b> command is part of the shadow-utils package, which superseded earlier password management utilities in Unix-like systems. It was developed to enhance security by allowing for shadowed passwords (passwords stored in a file readable only by root, typically <i>/etc/shadow</i>) and comprehensive password aging policies. Its introduction centralized and standardized password aging management, moving away from systems where such policies were less granular or harder to enforce.


title: SYNOPSIS
content:
<b>chardet</b> [<i>options</i>] [<i>file</i> ...]<br>If no <i>file</i> arguments are provided, <b>chardet</b> reads from standard input.


title: PARAMETERS
content:
<b><i>file</i> [<i>file</i> ...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies one or more paths to the text files whose encoding needs to be detected. If omitted, <b>chardet</b> reads from standard input.<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a brief help message detailing command usage and available options, then exits.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs the program's version number and exits.<br><br>


title: DESCRIPTION
content:
<b>chardet</b> is a command-line utility that leverages the powerful <i>chardet</i> Python library, which in turn is based on Mozilla's <i>UniversalCharDet</i> project. Its primary function is to intelligently guess the character encoding of a given text file or data streamed via standard input.<br><br>This tool is invaluable when dealing with text files that lack explicit encoding information, such as a Byte Order Mark (BOM) or other metadata. By statistically analyzing byte sequences within the file, <b>chardet</b> attempts to identify the most probable encoding (e.g., <b>UTF-8</b>, <b>Latin-1</b>, <b>Shift_JIS</b>, etc.).<br><br>The output typically includes the detected encoding name and a confidence level (a percentage), indicating the probability of the guess being correct. While highly effective for a wide range of common encodings, it's crucial to remember that encoding detection is a heuristic process, meaning it's an educated guess and not always 100% accurate, especially for short or ambiguous content.


title: CAVEATS
content:
<b>chardet</b> relies on heuristic analysis; therefore, its detection is an educated guess and not always definitive. Accuracy can be lower for very short files, files with limited character diversity, or content that is ambiguous between multiple encodings. It may occasionally misidentify encodings, especially for uncommon or custom character sets. While generally fast, processing extremely large files might consume significant memory or time.


title: HISTORY
content:
The underlying <i>chardet</i> library originated from Mozilla's <i>UniversalCharDet</i>, developed as part of the Firefox web browser to handle various character encodings found on the web. The Python binding, known as <i>python-chardet</i>, made this robust detection capability accessible to Python developers. The <b>chardet</b> command-line utility is typically provided as a simple wrapper script within the <i>python-chardet</i> package, allowing users to leverage the library's power directly from the shell without writing Python code. Its adoption grew significantly with the increasing need to correctly interpret and process text data from diverse sources and locales, becoming a standard tool for character encoding identification.


title: SYNOPSIS
content:
The term 'charm' refers to a software package managed by the <i>juju</i> command-line tool. It is not a standalone command. To interact with charms, one typically uses the <i>juju</i> command. For example:<br><br><b>juju deploy</b> <I>&lt;charm-name&gt;</I> <I>[options]</I><br><br>This command deploys an application using a specified charm.<br><br>Another common interaction is building charms:<br><br><b>juju build</b> <I>&lt;charm-path&gt;</I> <I>[options]</I><br><br>This command builds a charm bundle from a local directory.<br><br>To explore available charms:<br><br><b>juju charms</b> <I>[options]</I>


title: PARAMETERS
content:
<b><b>--channel</b> <I>&lt;track&gt;/[risk]/[branch]</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the release channel for the charm (e.g., stable, beta, edge). Used with <b>juju deploy</b>.<br><br><b><b>--series</b> <I>&lt;series&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Defines the operating system series (e.g., focal, jammy) on which to deploy the charm. Used with <b>juju deploy</b> or <b>juju build</b>.<br><br><b><b>--config</b> <I>&lt;key&gt;=&lt;value&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets configuration options for the deployed charm. Can be specified multiple times. Used with <b>juju deploy</b>.<br><br><b><b>--resource</b> <I>&lt;resource-name&gt;=&lt;resource-path-or-id&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a resource for the charm, typically for bundled files. Used with <b>juju deploy</b> or <b>juju build</b>.<br><br><b><b>--storage</b> <I>&lt;name&gt;=&lt;pool&gt;,&lt;size&gt;,&lt;count&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Attaches storage to the deployed charm. Used with <b>juju deploy</b>.<br><br><b><b>--force</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces an action, such as building a charm even if warnings are present. Used with <b>juju build</b>.<br><br><b><b>--search</b> <I>&lt;keywords&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Searches for charms in the Charmhub based on keywords. Used with <b>juju charms</b>.<br><br><b><b>--format</b> <I>&lt;format&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the output format (e.g., json, yaml, tabular). Used with <b>juju charms</b>.<br><br>


title: DESCRIPTION
content:
In the Linux ecosystem, 'charm' primarily refers to a Juju Charm, a powerful concept within Canonical's Juju orchestration tool. Juju Charms are essentially bundles of operational knowledge, scripts, and metadata that encapsulate how to deploy, configure, connect, scale, and upgrade a specific software application. They abstract away the complexity of managing applications across various cloud environments, Kubernetes, or bare-metal servers. A charm defines the application's lifecycle and its relationships with other applications, enabling automated deployment and management. Developers create charms to make their software easily deployable and maintainable, while operators use them to deploy and manage complex multi-application topologies with simple commands, ensuring best practices and reducing operational burden. They are written using a framework, typically in Python, and provide hooks that Juju executes during different lifecycle events.


title: CAVEATS
content:
The term 'charm' itself is not an executable Linux command. It refers to a specific type of application package managed by the <b>juju</b> orchestration tool. Therefore, direct execution of 'charm' in a terminal will result in 'command not found'. All interactions with charms are performed through the <b>juju</b> command and its subcommands. Juju and its charms require proper setup of a Juju controller and a cloud/Kubernetes environment.


title: JUJU CHARMHUB
content:
The Charmhub (<I>charmhub.io</I>) is the official store and repository for Juju Charms. It provides a vast collection of ready-to-deploy charms for popular software, developed by Canonical, vendors, and the community. Operators can search for, download, and deploy charms directly from Charmhub using the <b>juju deploy</b> command. It serves as a central point for discovering and sharing operational knowledge encapsulated in charms.


title: CHARMED OPERATORS
content:
While 'charm' is a general term, specifically when deployed on Kubernetes, they are often referred to as 'Charmed Operators' or 'K8s Charms'. These leverage the Kubernetes Operator pattern but add Juju's unique orchestration capabilities, providing more sophisticated lifecycle management, cross-application relations, and multi-cloud portability beyond what a typical Kubernetes Operator might offer.


title: HISTORY
content:
The concept of Juju Charms was introduced by Canonical as part of its Juju orchestration framework. Juju (originally called 'Ensemble') was first released around 2010. Charms were designed to encapsulate operational best practices and automate the deployment and management of applications across various infrastructures. Over time, charms have evolved significantly, moving from an older 'hooks' based system to a more modern 'Operator Framework' paradigm, which allows for more complex and robust operational logic. This evolution has made charms highly versatile, capable of managing applications not only on traditional cloud instances and bare metal but also extensively on Kubernetes clusters (where they are known as Charmed Operators). The Charmhub, an online store for charms, was launched to provide a centralized repository for community and vendor-published charms.


title: PARAMETERS
content:
<b>-A, --show-all</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Equivalent to <i>-vET</i>, shows non-printing characters, tabs, and line endings.<br><br><b>-b, --number-nonblank</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Number non-blank output lines, starting at 1. Overrides <i>-n</i>.<br><br><b>-E, --show-ends</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display <b>$</b> at the end of each line to indicate line breaks.<br><br><b>-n, --number</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Number all output lines, starting at 1.<br><br><b>-s, --squeeze-blank</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Squeeze multiple adjacent blank lines into a single blank line.<br><br><b>-T, --show-tabs</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display <b>TAB</b> characters as <b>^I</b>.<br><br><b>-u</b><br>&nbsp;&nbsp;&nbsp;&nbsp;(Ignored) This option is a POSIX standard for compatibility but has no effect on modern <b>cat</b> implementations as output is unbuffered by default.<br><br><b>-v, --show-nonprinting</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Use <b>^</b> and <b>M-</b> notation, except for line feed (LF) and tab (TAB), to show non-printing characters.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a help message and exit.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output version information and exit.<br><br>


title: DESCRIPTION
content:
The <b>cat</b> (short for "concatenate") command is a fundamental Unix and Linux utility. Its primary function is to read file content sequentially and write it to standard output. While its name implies concatenation, its most common modern usage is simply to display the content of one or more files directly to the terminal. Beyond mere viewing, <b>cat</b> is also widely used for combining multiple files into a single output stream or file, and for creating new files from standard input. It is an indispensable tool often employed in shell scripts and command pipelines, typically in conjunction with input/output redirection operators (like <b>&gt;</b> for overwriting, <b>&gt;&gt;</b> for appending) or pipes (<b>|</b>) to feed file content to other commands for further processing.


title: CAVEATS
content:
When dealing with very large files, <b>cat</b> loads the entire content into memory (or buffers it to standard output), which can be inefficient and consume significant resources. For interactive viewing of large files, commands like <b>less</b> or <b>more</b> are generally preferred as they allow scrolling and do not load the entire file at once.<br><br>Be cautious when redirecting output using the <b>&gt;</b> operator (e.g., cat file1 <b>&gt;</b> file2), as it will overwrite the destination file (<i>file2</i> in this example) without warning if it already exists. Use <b>&gt;&gt;</b> to append instead (e.g., cat file1 <b>&gt;&gt;</b> file2).


title: STANDARD INPUT/OUTPUT
content:
When no <i>FILE</i> is specified, or when <i>FILE</i> is given as a single hyphen (<b>-</b>), <b>cat</b> reads from its standard input until an end-of-file (EOF) signal is received (typically by pressing Ctrl+D). This makes it incredibly versatile for use in pipelines, where it can process output from other commands. For example, <code>command <b>|</b> cat - file2 <b>&gt;</b> combined_file</code> allows you to concatenate the output of 'command' with 'file2' into 'combined_file'.


title: HISTORY
content:
The <b>cat</b> command is one of the earliest Unix commands, predating the C programming language itself. It was originally implemented in assembly language for the PDP-7. Its name is derived from "concatenate," reflecting its initial primary purpose of joining files. While still capable of concatenation, its most prevalent modern use, displaying file contents on the standard output, was somewhat an unintended consequence of its design, often humorously referred to as an "abuse" by its original developers.


title: PARAMETERS
content:
<b><b>--prompt</b> <i>&lt;text&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The primary text query or instruction to send to the AI model. If omitted, the command might enter an interactive mode.<br><br><b><b>--model</b> <i>&lt;name&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the AI model to use for the request, e.g., <i>gpt-4</i>, <i>gpt-3.5-turbo</i>. Defaults to a commonly available model if not specified.<br><br><b><b>--stream</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs the AI response incrementally, character by character or word by word, as it is generated, similar to the web interface.<br><br><b><b>--continue</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Maintains the context of the previous conversation or session, allowing for multi-turn dialogues.<br><br><b><b>--api-key</b> <i>&lt;key&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides the API key for authentication with the AI service. Often, this can also be set via an environment variable (e.g., <i>OPENAI_API_KEY</i>).<br><br><b><b>--temperature</b> <i>&lt;value&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the randomness or creativity of the AI's response. A value between 0.0 (deterministic) and 1.0 (more creative), typically defaulting around 0.7.<br><br><b><b>--system</b> <i>&lt;text&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides an initial 'system' message to the AI, guiding its persona, instructions, or overall behavior for the conversation.<br><br><b><b>--history</b> <i>&lt;path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a custom file path for storing or loading conversation history.<br><br><b><b>--config</b> <i>&lt;path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a custom configuration file to load settings from.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message with usage instructions and available options for the command.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the version information of the installed <i>chatgpt</i> CLI tool.<br><br>


title: DESCRIPTION
content:
The <b>chatgpt</b> command refers to a category of community-developed command-line interface (CLI) tools that enable users to interact with large language models (LLMs), primarily OpenAI's GPT series, directly from their Linux terminal. <br><br>Unlike standard Linux utilities, <b>chatgpt</b> is not a built-in command but rather a third-party application, often written in <i>Python</i> or <i>Go</i>, that acts as a wrapper around the OpenAI API. It provides a convenient way to query AI models, generate code, summarize text, answer questions, and perform various AI-driven tasks without leaving the command line or relying on a web browser. <br><br>Users typically configure an API key (obtained from OpenAI) as an environment variable or via a configuration file to authenticate their requests. These tools aim to streamline workflows for developers, writers, and anyone who frequently interacts with AI, by integrating AI capabilities into a terminal-native environment.


title: CAVEATS
content:
The <i>chatgpt</i> command is <b>not a standard, pre-installed Linux utility</b>. It must be installed separately, usually via package managers for specific programming languages (like <i>pip</i> for <i>Python</i>) or by cloning a repository. <br><br>It requires an <b>active internet connection</b> and an <b>API key</b> from the respective AI service provider (e.g., OpenAI). API usage often incurs costs, billed by the AI service provider based on tokens consumed. Functionality and specific options may vary significantly between different community-contributed implementations of 'chatgpt' CLI tools.


title: HISTORY
content:
The concept of a 'chatgpt' command-line tool emerged rapidly following the widespread adoption of large language models like OpenAI's GPT series in late 2022 and early 2023. As developers and power users increasingly integrated AI into their workflows, there was a strong demand for direct terminal access to these models, bypassing web interfaces. This led to a proliferation of open-source projects designed to provide such an interface, often leveraging existing programming languages and their package managers. While no single 'chatgpt' command has become universally standard, many implementations share similar syntax and features, evolving to support new AI models and capabilities as they become available.


title: SYNOPSIS
content:
<b>chattr</b> [<i>-RVf</i>] [<i>-v</i> <i>version</i>] [<i>-L</i>] [<i>-P</i>] [<i>+|-|=</i><i>attributes</i>] <i>files...</i>


title: PARAMETERS
content:
<b><i>attributes</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more characters specifying the attribute(s) to add (<b>+</b>), remove (<b>-</b>), or set (<b>=</b>).<br>Common attributes include:<br>  <b>a</b>: <i>Append only</i>. Files can only be opened in append mode for writing.<br>  <b>i</b>: <i>Immutable</i>. File cannot be modified, deleted, renamed, or linked. No data can be written to the file.<br>  <b>A</b>: <i>No atime updates</i>. Disables updates to the file's access time.<br>  <b>S</b>: <i>Synchronous updates</i>. Changes are written to disk synchronously.<br>  <b>D</b>: <i>Synchronous directory updates</i>. For directories, changes are written synchronously.<br>  <b>c</b>: <i>Compress</i>. File is automatically compressed/decompressed (not widely supported or used).<br>  <b>s</b>: <i>Secure deletion</i>. When deleted, blocks are zeroed out (not guaranteed).<br>  <b>u</b>: <i>Undeletable</i>. Attempts to save file content on deletion (not guaranteed).<br>  <b>j</b>: <i>Data journaling</i>. All file data is written to the ext3 journal (deprecated on ext4).<br>  <b>t</b>: <i>No tail-merging</i>. Prevents small files from being merged into larger blocks.<br><br><b><b>-R</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Recursively changes attributes on directories and their contents.<br><br><b><b>-v</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the new version number of the file/directory. Use <b>-v</b> <i>version</i> to set a specific version.<br><br><b><b>-f</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppress most error messages.<br><br><b><b>-L</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;If a symbolic link is encountered, change attributes on the link itself instead of the target.<br><br><b><b>-P</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;When processing directories, change attributes on logical pathnames (default).<br><br>


title: DESCRIPTION
content:
<b>chattr</b> is a powerful Linux command used to modify extended file attributes on files and directories, primarily on <i>ext2, ext3, ext4</i>, and sometimes <i>XFS</i> or <i>Btrfs</i> filesystems.<br>Unlike standard Unix permissions (<b>chmod</b>), which control read, write, and execute access for different user categories, <b>chattr</b> allows setting more granular and often more restrictive attributes. These attributes are kernel-enforced, offering an additional layer of security and data integrity. For instance, making a file <i>immutable</i> (<b>+i</b>) prevents it from being deleted, renamed, modified, or linked, even by the root user, until the attribute is removed. Similarly, the <i>append-only</i> (<b>+a</b>) attribute allows a file to be opened only in append mode for writing. <b>chattr</b> is crucial for protecting critical system files, log files, or sensitive data from accidental or malicious alteration. Most significant attribute changes require superuser (root) privileges.


title: CAVEATS
content:
<b>chattr</b> attributes are filesystem-specific. They are primarily supported and most effective on <i>ext2/3/4</i> filesystems. While some attributes (<b>i</b>, <b>a</b>) might work on <i>XFS</i> or <i>Btrfs</i>, their behavior or support might vary.<br>Many critical attributes, especially <b>i</b> (immutable) and <b>a</b> (append-only), require <i>root privileges</i> to set or unset.<br>Misuse of <b>chattr</b>, particularly making critical system files immutable, can lead to system instability or prevent necessary updates and operations.<br>It is not a replacement for standard file permissions (<b>chmod</b>); it provides an additional, often more restrictive, layer of control.


title: COMMON USE CASES
content:
Protecting log files (e.g., <b>+a</b> for <i>/var/log/syslog</i> to only allow appending).<br>Preventing accidental deletion or modification of critical configuration files (e.g., <b>+i</b> for <i>/etc/fstab</i> or <i>/etc/resolv.conf</i>).<br>Securing sensitive data files from unauthorized changes, even by privileged users.


title: INTERACTION WITH ROOT
content:
The <b>i</b> (immutable) attribute is so strong that even the <i>root user cannot delete or modify</i> the file without first removing the attribute. This provides a significant security enhancement against rootkits or accidental system changes.


title: VIEWING ATTRIBUTES
content:
Use the <b>lsattr</b> command (e.g., <b>lsattr</b> <i>filename</i>) to view the attributes set on a file or directory.


title: HISTORY
content:
<b>chattr</b> is part of the <i>e2fsprogs</i> package, a set of utilities for managing the ext2, ext3, and ext4 filesystems. Its development has been closely tied to the evolution of these filesystems, especially since the introduction of attributes in ext2. While initially designed for ext filesystems, its utility led to some attributes being adopted or emulated on other modern Linux filesystems where applicable. Its core functionality has remained consistent, focusing on providing granular control over file behavior at the kernel level.


title: SYNOPSIS
content:
<b>chcon</b> [<i>OPTION</i>]... <i>CONTEXT FILE</i>...<br><b>chcon</b> [<i>OPTION</i>]... <b>--reference=</b><i>RFILE FILE</i>...<br><b>chcon</b> [<i>OPTION</i>]... <b>-u</b> <i>USER</i> <b>-r</b> <i>ROLE</i> <b>-t</b> <i>TYPE</i> <b>-l</b> <i>RANGE FILE</i>...


title: PARAMETERS
content:
<b><i>CONTEXT</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The target SELinux context (e.g., <i>user:role:type:sensitivity</i>).<br><br><b>-u, --user=<i>USER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the SELinux user component of the security context.<br><br><b>-r, --role=<i>ROLE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the SELinux role component of the security context.<br><br><b>-t, --type=<i>TYPE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the SELinux type component of the security context. This is often the most critical component for policy enforcement.<br><br><b>-l, --range=<i>RANGE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the SELinux sensitivity level or range (e.g., <i>s0, s0:c0.c1023</i>).<br><br><b>--reference=<i>RFILE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Use the security context of <i>RFILE</i> instead of specifying <i>CONTEXT</i> explicitly.<br><br><b>-R, --recursive</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Change contexts of files and directories recursively.<br><br><b>-v, --verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output a diagnostic for every file processed.<br><br><b>-f, --force</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppress most error messages.<br><br><b>-h, --no-dereference</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Affect symbolic links themselves instead of their targets.<br><br><b>-H</b><br>&nbsp;&nbsp;&nbsp;&nbsp;If a command line argument is a symbolic link to a directory, traverse it.<br><br><b>-L</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Traverse every symbolic link to a directory encountered.<br><br><b>-P</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not traverse any symbolic links (this is the default behavior).<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display help information and exit.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output version information and exit.<br><br>


title: DESCRIPTION
content:
The <b>chcon</b> command, standing for "change context," is a crucial utility in Linux systems employing SELinux (Security-Enhanced Linux). It allows system administrators to explicitly modify the SELinux security context of files, directories, and other file system objects. SELinux uses these contexts, which are extended attributes containing information like the SELinux user, role, type, and sensitivity level (e.g., <i>system_u:object_r:httpd_sys_content_t:s0</i>), to enforce mandatory access control (MAC) policies. Unlike traditional discretionary access control (DAC) permissions (read, write, execute), SELinux contexts provide a more granular and robust security mechanism.<br><br>When files are created or moved, they typically inherit contexts from their parent directories or the creating process. However, in certain scenarios, such as when copying files from external sources, restoring backups, or troubleshooting SELinux denials, the inherited context might be incorrect or insufficient. <b>chcon</b> enables administrators to correct these labels manually, ensuring that applications and services have the necessary permissions to access resources and that the system maintains its security posture according to the defined SELinux policy. Proper context labeling is essential for SELinux to function correctly and prevent unauthorized operations.


title: CAVEATS
content:
Using <b>chcon</b> requires a deep understanding of SELinux policies and contexts.<br><br>Incorrectly setting contexts can lead to significant system malfunctions, including applications failing to start, "Permission denied" errors for seemingly legitimate operations, or even system boot failures if critical system files are mislabeled.<br><br>It is generally safer and recommended to use the <b>restorecon</b> command to revert files to their default, policy-defined SELinux contexts, especially after restoring backups or moving files into standard locations, rather than manually setting contexts with <b>chcon</b> unless you have a specific, expert-level reason to do so. The changes made by <b>chcon</b> are immediate and persistent until explicitly changed again or reset by <b>restorecon</b>.


title: <I>CHCON VS. RESTORECON</I>
content:
While both commands manipulate SELinux contexts, <b>chcon</b> allows you to explicitly set a context to any value you specify. In contrast, <b>restorecon</b> is designed to reset file contexts to their default values, as defined by the installed SELinux policy. <b>restorecon</b> uses the policy rules to determine the correct context for a given file path, making it the preferred command for fixing labeling issues automatically rather than manually assigning labels with <b>chcon</b>.


title: <I>SELINUX CONTEXT STRUCTURE</I>
content:
An SELinux context is typically composed of four fields:<br><i><b>user</b></i>: Represents an SELinux user identity, often mapping to a Linux user.<br><i><b>role</b></i>: Defines a role that the user or process can assume, influencing what types they can access.<br><i><b>type</b></i>: The most crucial component for file system objects, defining the type of the object (e.g., <b>httpd_sys_content_t</b> for web content, <b>bin_t</b> for executables). SELinux policy rules are heavily based on types.<br><i><b>sensitivity[:category]</b></i>: Used for Multi-Level Security (MLS) or Multi-Category Security (MCS) and typically seen as <b>s0</b> for single-level systems or <b>s0:c0.c1023</b> for MCS.


title: HISTORY
content:
<b>chcon</b> is an integral part of the SELinux toolkit, which originated from the National Security Agency (NSA) as a research project to enhance security in Linux. It was integrated into the Linux kernel mainline in 2003. The <b>chcon</b> utility itself, along with <b>restorecon</b> and other SELinux management tools, is typically part of the <b>policycoreutils</b> package on distributions that heavily leverage SELinux, such as Red Hat Enterprise Linux (RHEL), CentOS, and Fedora. Its development has closely tracked the evolution and adoption of SELinux as a robust mandatory access control framework, becoming essential for administrators managing SELinux-enabled systems.


title: SEE ALSO
content:
<b>restorecon</b>(8), <b>semanage</b>(8), <b>ls</b>(1) -Z option, <b>ps</b>(1) -Z option, <b>chown</b>(1), <b>chmod</b>(1)


title: PARAMETERS
content:
<b><b>-e</b>, <b>--enable</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables the specified CPU(s), bringing them online for scheduling.<br><br><b><b>-d</b>, <b>--disable</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables the specified CPU(s), taking them offline from scheduling.<br><br><b><b>-a</b>, <b>--all</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Applies the <b>--enable</b> or <b>--disable</b> action to all detected CPUs. Cannot be used alone.<br><br><b><b>-r</b>, <b>--reboot-cpu</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Attempts to reboot the specified CPU(s) or all CPUs if <b>--all</b> is used. This is a highly platform-dependent feature.<br><br><b><b>-s</b>, <b>--status</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the current online/offline status for all detected CPU cores.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a help message and exits.<br><br><b><b>-V</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints version information and exits.<br><br><b><i>cpu_id</i>...</b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more numerical CPU IDs (e.g., 0, 1, 2) to operate on. CPU IDs can be found via <b>lscpu</b>.<br><br>


title: DESCRIPTION
content:
<i><b>chcpu</b></i> is a command-line utility included in the <i>util-linux</i> package, designed for managing the online and offline states of CPU cores within a Linux system. It provides a convenient way for system administrators to enable or disable specific CPUs dynamically, without requiring a system reboot. This functionality is invaluable for various administrative tasks, including optimizing power consumption, isolating potentially faulty CPU cores, testing system resilience under reduced CPU availability, or fine-tuning resource allocation for particular workloads.<br><br>When a CPU is disabled using <i><b>chcpu</b></i>, it is taken offline by the kernel and will no longer be considered for task scheduling. Conversely, enabling a CPU brings it back online, making it available for the scheduler. The command leverages the Linux <i>sysfs</i> filesystem, specifically by interacting with the <i>/sys/devices/system/cpu/cpuX/online</i> file for each CPU ID <i>X</i>. Due to its direct interaction with core system hardware, executing <i><b>chcpu</b></i> requires root privileges.


title: CAVEATS
content:
Using <i><b>chcpu</b></i> requires root (superuser) privileges. Attempting to disable <i>cpu0</i> (the primary CPU) is generally disallowed by the kernel and the command itself, as it can lead to system instability or crashes. The <b>--reboot-cpu</b> option is highly dependent on specific kernel and hardware support, and its functionality may vary or be unavailable on many systems. Modifying CPU states can impact overall system performance and resource allocation, so caution is advised.


title: UNDERLYING MECHANISM
content:
<i><b>chcpu</b></i> operates by writing '<b>1</b>' (online) or '<b>0</b>' (offline) to the <i>online</i> file located at <i>/sys/devices/system/cpu/cpuX/online</i> for the specified CPU <i>X</i>. This <i>sysfs</i> interface is the standard and direct method for user-space applications to control the online state of individual CPU cores.


title: CPU IDENTIFICATION
content:
CPU IDs are typically numerical, starting from '<b>0</b>' and incrementing (e.g., 0, 1, 2...). You can determine the available CPU IDs on your system by using the <b>lscpu</b> command or by examining the directory names within <i>/sys/devices/system/cpu/</i>.


title: HISTORY
content:
<i><b>chcpu</b></i> is an integral part of the widely used <i>util-linux</i> project, which aggregates essential system utilities for Linux. Its development and utility gained prominence as the Linux kernel evolved to support CPU hotplugging capabilities, allowing for dynamic management of CPU resources without requiring a full system reboot. The command's functionality is deeply intertwined with the kernel's <i>sysfs</i> interface, which provides the underlying programmatic access to control CPU states. It serves as a specialized tool primarily for system administrators engaged in advanced power management, performance optimization, or hardware troubleshooting.


title: PARAMETERS
content:
<b><i>sheet-name</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The name of the cheat sheet to display, edit, create, or delete.<br><br><b><b>-l</b>, <b>--list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists all available cheat sheets in the configured directories.<br><br><b><b>-s</b> <<i>keyword</i>>, <b>--search</b> <<i>keyword</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Searches for cheat sheets containing the specified keyword in their content or name.<br><br><b><b>-e</b> <<i>sheet-name</i>>, <b>--edit</b> <<i>sheet-name</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Opens the specified cheat sheet in your default text editor (<i>$EDITOR</i>). If the sheet does not exist, it will be created.<br><br><b><b>-c</b> <<i>sheet-name</i>>, <b>--create</b> <<i>sheet-name</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Creates a new, empty cheat sheet with the given name. Equivalent to <b>-e</b> if the sheet doesn't exist.<br><br><b><b>-d</b> <<i>sheet-name</i>>, <b>--delete</b> <<i>sheet-name</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Deletes the specified cheat sheet from your collection.<br><br><b><b>-p</b>, <b>--paths</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the paths where <b>cheat</b> looks for cheat sheets.<br><br><b><b>-T</b> <<i>template-name</i>>, <b>--template</b> <<i>template-name</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;When creating a new cheat sheet, use an existing cheat sheet as a template.<br><br><b><b>-f</b>, <b>--force</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces an action, such as overwriting an existing cheat sheet when creating with a template.<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the current version of the <b>cheat</b> command.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the help message and exits.<br><br>


title: DESCRIPTION
content:
The <b>cheat</b> command is a versatile command-line utility designed to help users create, view, and manage their own custom cheat sheets directly from the terminal. It's an invaluable tool for programmers, system administrators, and anyone who frequently uses the command line and needs quick access to syntax, commands, or procedural notes.<br><br>Users can easily define cheat sheets for various commands, programming languages, or specific tasks. When invoked, <b>cheat</b> displays the content of a requested cheat sheet, allowing for rapid recall of information without needing to consult lengthy man pages or external documentation. Its integration with the user's preferred text editor (via the <i>$EDITOR</i> environment variable) makes creating and modifying these personal knowledge bases intuitive and efficient. It supports searching, listing available sheets, and managing them through simple commands.


title: CAVEATS
content:
The <b>cheat</b> command relies on your <i>$EDITOR</i> environment variable being set for editing functionality. If it's not set, editing will not work. Additionally, cheat sheets are stored as plain text files, meaning sensitive information should not be stored unencrypted within them. Users are responsible for managing their cheat sheet directories and permissions.


title: CONFIGURATION
content:
<b>cheat</b>'s behavior can be customized by setting the <i>$CHEATPATHS</i> environment variable, which defines the directories where <b>cheat</b> looks for cheat sheets. By default, it checks <i>~/.cheat</i> and system-wide paths. Users can also configure a preferred editor by setting the <i>$EDITOR</i> environment variable (e.g., <i>export EDITOR=nvim</i>).


title: CREATING CUSTOM SHEETS
content:
To create a new cheat sheet, simply run <b>cheat -e</b> <i>&lt;sheet-name&gt;</i>. This will open your editor, where you can type your notes. The content is saved as plain text. It's recommended to organize sheets by command name (e.g., 'git', 'awk', 'tar') or topic (e.g., 'networking', 'docker').


title: HISTORY
content:
The <b>cheat</b> command-line utility was created by Chris Allen as a Python-based open-source project. Its development began with the goal of providing a simple, customizable, and fast way for developers and sysadmins to store and retrieve personal command-line notes. Over time, it has gained popularity as a lightweight alternative to more complex documentation systems, focusing on user-generated content and easy accessibility directly from the terminal.


title: PARAMETERS
content:
<b><i>-h</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display help message and exit.<br><br><b><i>-q</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enable quiet mode, suppressing the welcome message.<br><br><b><i>-v</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enable verbose mode, showing the URL being queried.<br><br><b><i>-i</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enter interactive search and browsing mode.<br><br><b><i>-L</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;List all available topics and commands.<br><br><b><i>-s SERVER_URL</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a custom cheat.sh server URL. This allows using a local instance or a mirror.<br><br><b><i>-p</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a random cheat sheet page.<br><br><b><i>TOPIC</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The main command, language, or general topic to query (e.g., 'ls', 'python', 'git').<br><br><b><i>TOPIC</i>/<i>SUBTOPIC</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Query a specific sub-section or aspect within a topic (e.g., 'git/branch' or 'tar/extract').<br><br><b><i>TOPIC</i>?<i>QUERY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Search for a specific keyword or phrase within the provided topic (e.g., 'grep?recursive').<br><br><b><i>TOPIC</i>~<i>QUERY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Perform a fuzzy search for a query within the provided topic (e.g., 'tar~compress').<br><br><b><i>TOPIC</i>/<i>NUMBER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Retrieve the Nth example for a given topic (e.g., 'tar/3' to get the third example for 'tar').<br><br><b><i>TOPIC</i><b>:</b><i>PAGER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Pipe the output for a topic to a specified pager command (e.g., 'ls:less' to view 'ls' cheat sheet in less).<br><br><b><i>TOPIC</i><b>:</b><i>SHELL</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Request output formatted for a specific shell (e.g., 'python/:bash' for bash-specific python examples).<br><br><b><i>TOPIC</i>@<i>VERSION</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Retrieve examples specific to a certain version of a topic (e.g., 'python@3.9').<br><br><b><i>TOPIC</i>#<i>TAG</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Filter examples by a specific tag within a topic (e.g., 'docker#network').<br><br>


title: DESCRIPTION
content:
<i>cheatsh</i> (or <i>cht.sh</i>) is a powerful and highly versatile command-line utility designed to provide quick and comprehensive cheat sheets directly within your terminal. It serves as an invaluable resource for developers, system administrators, and anyone working frequently with the command line, offering immediate access to syntax, common usage patterns, and practical examples for thousands of Linux commands, programming languages, and various technical topics.<br><br>Instead of browsing traditional documentation or searching the web, <i>cheatsh</i> allows users to retrieve concise, relevant information by simply typing <b>cheatsh &lt;topic&gt;</b>. It fetches data from a remote server (by default, <i>https://cheat.sh</i>), which aggregates and curates information from various open-source projects and contributions. Its interactive mode, extensive search capabilities, and support for specific shell outputs make it an indispensable tool for boosting productivity and understanding complex commands on the fly. It's particularly useful for recalling infrequently used command options or quickly grasping new concepts.


title: CAVEATS
content:
<i>cheatsh</i> primarily relies on internet connectivity to fetch cheat sheets from the <i>cheat.sh</i> server. While the server is generally considered reliable and secure, users should be mindful that they are retrieving content from a remote source.<br>The comprehensiveness and accuracy of the information depend on the content curated and contributed to the <i>cheat.sh</i> service.


title: DIRECT CURL ACCESS
content:
The underlying <i>cht.sh</i> service can be accessed directly using <i>curl</i>, without installing the <i>cheatsh</i> client. For example, <b>curl cht.sh/tar</b> will display the cheat sheet for the <i>tar</i> command directly in your terminal. This is often used for quick, one-off lookups or in scripts.


title: CUSTOMIZATION AND ALIASING
content:
Users often create shell aliases (e.g., <b>alias cht='cheatsh'</b>) for quicker access. The default server URL can also be configured (via the <b>-s</b> option or an environment variable) to point to a local mirror or a different server.


title: HISTORY
content:
<i>cheatsh</i> is a client-side wrapper for the highly popular <i>cht.sh</i> service, developed by Igor Chubin (<i>chubin</i> on GitHub). The <i>cht.sh</i> service itself emerged as a simple yet powerful way to get instant command-line help, popularized by its 'curlable' nature (i.e., `curl cht.sh/<i>topic</i>`).<br><br>The standalone <i>cheatsh</i> client was created to provide a more refined user experience, offering features like interactive mode, persistent settings, and better integration with the terminal environment, building upon the robust backend of the <i>cht.sh</i> web service. Its development has been community-driven, growing into an indispensable tool for terminal users globally.


title: SYNOPSIS
content:
<br><b>check-dfsg-status</b> [<i>OPTION</i>...] [<i>FILE</i>...]<br><b>check-dfsg-status</b> [<i>OPTION</i>...] <b>--package</b> <i>PACKAGE</i>


title: PARAMETERS
content:
<b>-v, --verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Produce more detailed output, showing additional information about the checks performed.<br><br><b>-q, --quiet</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppress most output, showing only critical errors or warnings.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a concise help message with available options and exit.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Show the version information for the command and exit.<br><br><b>--package <I>PACKAGE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Check the DFSG status of an entire Debian source package rather than individual files or a directory.<br><br><b>--upstream-tarball <I>PATH</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the path to the original upstream source tarball, which might be analyzed for DFSG compliance issues.<br><br><b>--rules-dir <I>PATH</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify an alternative directory where packaging rules (e.g., <I>debian/rules</I>) are located, potentially influencing the checks.<br><br><b>--profile <I>PROFILE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a Lintian profile to use for checks, tailoring the type and strictness of the DFSG analysis.<br><br><b>--dfsg-status-dir <I>DIR</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the directory where DFSG status files (<I>.dfsg-status</I>) are located or where they should be stored.<br><br>


title: DESCRIPTION
content:
The <I>check-dfsg-status</I> command is a utility within the Debian project, primarily used by package maintainers and developers. Its core function is to analyze and report on the DFSG (Debian Free Software Guidelines) compliance status of files, directories, or entire packages. It often works by reading <I>.dfsg-status</I> files, which are typically generated by tools like <I>lintian</I> or manually maintained. These files document the licensing and freedom status of various upstream components, especially when a software package might contain elements (e.g., firmware blobs, non-free images, restricted fonts) that do not fully adhere to the DFSG. By using this command, developers can ensure that their packages conform to Debian's strict free software principles before uploading them to the archive. It helps identify and address potential issues related to non-free content, ensuring Debian's commitment to free software.


title: CAVEATS
content:
This command is primarily a developer tool and relies on specific Debian packaging conventions and the existence of <I>.dfsg-status</I> files, which are often generated by <I>lintian</I> or manually maintained. Its output requires an understanding of Debian's DFSG and package structure. It is not intended for general end-user use for checking arbitrary software freedom.


title: DFSG IMPORTANCE
content:
The Debian Free Software Guidelines (DFSG) are a set of principles that define what software is considered 'free' for inclusion in the Debian project. These guidelines are crucial for Debian's identity as a 100% free operating system. <I>check-dfsg-status</I> directly supports the enforcement of these guidelines, making it a vital tool in maintaining the integrity and freedom of the Debian archive.


title: .DFSG-STATUS FILES
content:
These are plain text files, often found within a Debian package's source tree (e.g., <I>debian/.dfsg-status</I>). They contain line-by-line entries detailing the DFSG status of specific files or components from the upstream source. For instance, they might declare certain firmware blobs as 'non-free' but acceptable due to their necessity for hardware, or explicitly state that a bundled library is 'free'. <I>check-dfsg-status</I> reads and interprets these declarations to provide an overall compliance report for a package or its components.


title: HISTORY
content:
The <I>check-dfsg-status</I> command is an integral part of the <I>lintian</I> project, which was initiated in the late 1990s (around 1998-1999) to provide automated checks for Debian packages. As Debian's commitment to the Free Software Guidelines (DFSG) became a cornerstone of its distribution, specialized tools were needed to verify compliance, especially for complex upstream sources that might mix free and non-free components. <I>check-dfsg-status</I> evolved to address this specific need, providing a systematic way to manage and verify the DFSG status of various package components. Its development reflects Debian's ongoing efforts to ensure its archive remains entirely free software.


title: PARAMETERS
content:
<b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits the program.<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the program's version number and exits.<br><br><b><b>-l</b> <i>language_code</i>, <b>--language</b>=<i>language_code</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Checks language support specifically for the provided <i>language_code</i> (e.g., 'es' for Spanish).<br><br><b><b>-c</b>, <b>--check</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Performs a comprehensive check to ensure all installed languages are fully supported on the system.<br><br><b><b>-d</b>, <b>--dry-run</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Simulates the actions that would be performed without making any actual changes to the system.<br><br><b><b>--status-file</b>=<i>file</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Uses the specified <i>file</i> to report the status of the language support check.<br><br><b><b>--apt-cache-file</b>=<i>file</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Utilizes a specific APT cache <i>file</i> for retrieving package information, overriding the default.<br><br><b><b>--print-missing-language-packs</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs a list of language packs that are identified as missing for the configured languages.<br><br><b><b>--print-status</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the overall status of the language support check to standard output.<br><br><b><b>--no-daemon-reload</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prevents the systemd daemon from reloading after operations, useful for debugging or specific scenarios.<br><br>


title: DESCRIPTION
content:
The <b>check-language-support</b> command is a specialized utility primarily found on Debian and Ubuntu-based Linux distributions. It serves as a crucial component of the <i>language-selector-common</i> package, which facilitates the management and installation of language packs for various locales. Unlike generic system commands, <b>check-language-support</b> is specifically designed to assess the completeness of language support on a system. <br><br> Its core function involves verifying whether all necessary language packs, fonts, and input method components are correctly installed and configured for the languages chosen by the user. This often includes checking against a list of officially supported languages, typically stored in files like <i>/var/lib/language-selector/supported-languages</i>. When invoked, it identifies any discrepancies, such as missing translations for installed applications, incomplete font support, or misconfigured locale settings that could hinder a fully localized user experience. <br><br> While it can be run from the command line, its primary role is as a backend tool for graphical language settings applications, such as <i>language-selector-gnome</i>. These frontends utilize <b>check-language-support</b> to present users with an intuitive interface to add, remove, or repair language installations, ensuring that the system's language environment is consistent and functional. This command is vital for users who operate their systems in multiple languages or require robust localization features, preventing issues like untranslated menu items, incorrect date formats, or problems with character rendering. It significantly simplifies the often complex task of setting up comprehensive linguistic support in a desktop Linux environment.


title: CAVEATS
content:
<i>check-language-support</i> is not a universally available Linux command; it is primarily found and actively maintained within Debian and Ubuntu-based distributions as part of the <i>language-selector-common</i> package. Its utility is largely focused on desktop environments rather than headless server installations, as its main purpose is to ensure comprehensive graphical and textual localization for users. Furthermore, its functionality is tightly integrated with the <i>language-selector</i> suite of tools, meaning its standalone use might be less intuitive or effective for complex localization tasks without understanding the broader system it operates within.


title: TYPICAL USAGE CONTEXT
content:
While <i>check-language-support</i> can be executed directly from a terminal, its most common and intended use is as a backend component for graphical user interfaces like <i>language-selector-gnome</i>. These frontends provide a user-friendly way to manage installed languages, and they rely on <i>check-language-support</i> to perform the actual verification of language pack integrity and system configuration, often prompting users to install missing components or fix issues.


title: SUPPORTED LANGUAGES FILE
content:
The command frequently references the file located at <i>/var/lib/language-selector/supported-languages</i>. This file contains a list of language codes that are officially recognized and supported by the language-selector system. <i>check-language-support</i> uses this list to validate user-selected languages against available language packs and ensure that the system adheres to the distribution's localization standards.


title: HISTORY
content:
The <i>check-language-support</i> command's development is intrinsically linked to the evolution of desktop localization efforts within the Ubuntu and Debian ecosystems. It emerged as a crucial component of the <i>language-selector</i> suite, designed to simplify and automate the often intricate process of ensuring full language support for users. Before such integrated tools, configuring language environments, including installing correct fonts, translation files, and input methods, was a manual and error-prone task. <i>check-language-support</i> was specifically crafted to provide a robust backend for graphical language settings applications, allowing for programmatic checks and rectification of language support issues. Its continuous development reflects the ongoing commitment to making Linux more accessible and user-friendly for a global audience, ensuring that linguistic preferences are seamlessly integrated into the operating system experience.


title: PARAMETERS
content:
<b>--json</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs the support status information in JSON format, suitable for scripting.<br><br><b>--full-json</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides a more verbose JSON output, including detailed information about each service.<br><br><b>--color</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces colored output, even if the terminal doesn't seem to support it.<br><br><b>--no-color</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables colored output.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the version of the <b>ubuntu-advantage-tools</b> package.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a help message and exits.<br><br>


title: DESCRIPTION
content:
<i>check-support-status</i> is a utility specifically designed for Ubuntu systems to query and display the current status of various Ubuntu Pro services and entitlements. These services include Extended Security Maintenance (ESM) for packages, kernel Livepatch, FIPS compliance, and other enterprise-grade features provided by Canonical. It provides an at-a-glance overview of which Pro features are enabled, disabled, or available on the system.<br><br>The command is part of the <b>ubuntu-advantage-tools</b> package and is crucial for administrators managing Ubuntu servers and desktops within an Ubuntu Pro ecosystem, ensuring that critical security updates and features are active and properly configured. It helps in quickly identifying if a system is receiving the necessary support and updates.


title: CAVEATS
content:
<i>check-support-status</i> is <b>not</b> a standard, universally available Linux command. It is specific to Ubuntu and other Debian-based systems that have the <b>ubuntu-advantage-tools</b> package installed and are participating in the Ubuntu Pro ecosystem.<br>Its functionality relies on an active Ubuntu Pro subscription or an enabled Ubuntu Advantage free tier for personal use, which requires a connection to Canonical's servers for authentication and service status checks.<br>Running this command on a system without these prerequisites will likely result in an error or a message indicating that Ubuntu Pro is not enabled.


title: OUTPUT INTERPRETATION
content:
The command typically displays a clear table indicating the status of various services like ESM Apps, ESM Infra, Livepatch, FIPS, etc. Statuses can include <b>'enabled'</b> (active and providing benefits), <b>'disabled'</b> (not active), or <b>'available'</b> (can be enabled with <i>ua enable &lt;service&gt;</i>). An 'error' status indicates a problem querying the service.


title: DEPENDENCIES
content:
This command is provided by the <b>ubuntu-advantage-tools</b> package, which must be installed on your Ubuntu system. This package also includes the <i>ua</i> (or <i>pro</i>) command-line client, which is used for enabling and disabling Ubuntu Pro services.


title: HISTORY
content:
The <i>check-support-status</i> command emerged as part of Canonical's <b>ubuntu-advantage-tools</b> suite. This suite was developed to provide and manage commercial support features for Ubuntu users, particularly focusing on enterprise environments. Its development paralleled the growth of Ubuntu Pro, which offers Extended Security Maintenance (ESM), kernel Livepatching, FIPS 140-2 compliance, and other enhanced services. The command serves as a quick diagnostic tool within this ecosystem, allowing administrators to verify the active status of these critical support features on their systems, ensuring compliance and security.


title: SYNOPSIS
content:
<b>checkinstall</b> [<i>options</i>] [-- <i>arguments</i>]<br><br>Typical usage:<br>1. Configure and build the software: <i>./configure && make</i><br>2. Run checkinstall: <i>sudo checkinstall [options]</i> (then follow prompts for the install command, e.g., <i>make install</i>)<br>3. Alternatively, specify the install command directly: <i>sudo checkinstall [options] make install</i>


title: PARAMETERS
content:
<b><b>-D</b>, <b>--type=debian</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Create a Debian (<i>.deb</i>) package. This is often the default on Debian-based systems.<br><br><b><b>-R</b>, <b>--type=rpm</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Create a Red Hat (<i>.rpm</i>) package. This is often the default on Red Hat-based systems.<br><br><b><b>-S</b>, <b>--type=slackware</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Create a Slackware (<i>.tgz</i>) package. This is often the default on Slackware systems.<br><br><b><b>--install=no</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not install the generated package immediately after creation. Just build the package file.<br><br><b><b>--default</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Accept all default answers without prompting the user for information (e.g., package name, version, description).<br><br><b><b>--fstrans=no</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not perform filesystem translation (e.g., <i>/usr/local</i> to <i>/usr</i>). Use with caution, as it can lead to non-standard package structures.<br><br><b><b>--pkgname=&lt;name&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the name of the package. If not provided, <b>checkinstall</b> attempts to guess it.<br><br><b><b>--pkgversion=&lt;version&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the version of the package.<br><br><b><b>--pkgrelease=&lt;release&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the release number of the package (e.g., for updates).<br><br><b><b>--maintainer=&lt;email&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the email address of the package maintainer.<br><br><b><b>--nodoc</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not include documentation files in the generated package.<br><br><b><b>--backup=no</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not create backups of files that are modified or overwritten during installation.<br><br><b><b>--provides=&lt;string&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Add a 'Provides' entry to the package metadata, indicating capabilities or virtual packages it provides.<br><br><b><b>--requires=&lt;string&gt;</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Add a 'Requires' entry to the package metadata, specifying package dependencies.<br><br>


title: DESCRIPTION
content:
<b>checkinstall</b> is a program that monitors an <i>install</i> command (like <i>make install</i>) and creates a standard package (such as a <i>.deb</i>, <i>.rpm</i>, or <i>.tgz</i> file) from the files that would have been installed. <br><br>Instead of scattering files directly into your system directories, <b>checkinstall</b> bundles them into a package. This package can then be installed using your distribution's native package manager (e.g., <i>dpkg</i>, <i>rpm</i>, <i>installpkg</i>). This approach offers significant benefits: <br>1. <b>Easy Uninstallation:</b> The software can be cleanly removed using the package manager. <br>2. <b>System Cleanliness:</b> Avoids polluting your system with untracked files. <br>3. <b>Reusability:</b> The generated package can be installed on other compatible systems. <br><br>It's particularly useful when you need to install software not available in your distribution's repositories, or a specific version of a program, providing a cleaner alternative to a direct <i>make install</i>.


title: CAVEATS
content:
1. <b>Build Dependencies:</b> <b>checkinstall</b> does not resolve or manage build-time dependencies. You must ensure all necessary development tools and libraries are installed before running <i>make</i>.<br>2. <b>Complex Installations:</b> It may not perfectly handle highly complex installation procedures that involve intricate scripting, modifications to system configuration files outside typical installation paths, or user-specific setups.<br>3. <b>Not a Replacement for Proper Packaging:</b> While convenient, it's not a substitute for creating official, robust packages using tools like <i>debhelper</i> or <i>rpmbuild</i>, especially for distribution to a wider audience.<br>4. <b>Root Privileges:</b> It must be run as root (or with <i>sudo</i>) because it needs to monitor system calls and write to system directories.


title: TYPICAL USAGE FLOW
content:
The general workflow for using <b>checkinstall</b> is: <br>1. Download and extract the source code. <br>2. Navigate into the source directory. <br>3. Run the configuration step (e.g., <i>./configure</i>). <br>4. Compile the software (e.g., <i>make</i>). <br>5. Execute <b>checkinstall</b> (e.g., <i>sudo checkinstall</i>), which will then prompt you for the installation command (typically <i>make install</i>) and package metadata. It then wraps the installation, creates the package, and optionally installs it.


title: OUTPUT PACKAGE LOCATION
content:
By default, the generated package file (<i>.deb</i>, <i>.rpm</i>, or <i>.tgz</i>) is created in the directory where you run <b>checkinstall</b>. After creation, you can manually install it on other compatible systems using the appropriate package manager.


title: HISTORY
content:
<b>checkinstall</b> was developed as a pragmatic solution for users who wanted to install software from source code but also wished to retain the benefits of a package management system, primarily for clean uninstallation. It filled a gap between the often 'dirty' <i>make install</i> and the more complex process of creating full-fledged native packages. Its focus has always been on ease of use and practicality for individual users and system administrators installing custom software.


title: SYNOPSIS
content:
<b>checkov</b> [<i>OPTIONS</i>] <<i>PATH_OR_FILE</i>><br>Examples:<br>&nbsp;&nbsp;<b>checkov</b> <b>--directory</b> <i>/path/to/iac/code</i><br>&nbsp;&nbsp;<b>checkov</b> <b>-f</b> <i>my_terraform_file.tf</i> <b>--framework</b> <i>terraform</i><br>&nbsp;&nbsp;<b>checkov</b> <b>-d</b> <i>.</i> <b>--skip-checks</b> <i>CKV_AWS_1,CKV_K8S_2</i> <b>-o</b> <i>json</i>


title: PARAMETERS
content:
<b>--directory (-d)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Path to a directory containing IaC files to scan.</i><br><br><b>--file (-f)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Path to a specific IaC file to scan.</i><br><br><b>--framework (-f)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Specify the IaC framework to scan (e.g., terraform, cloudformation, kubernetes, dockerfile). Can be specified multiple times.</i><br><br><b>--skip-checks (-s)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Comma-separated list of check IDs to skip (e.g., CKV_AWS_1,CKV_K8S_2).</i><br><br><b>--output (-o)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Output format for scan results (e.g., cli, json, junitxml, sarif, github_checks).</i><br><br><b>--external-checks-dir</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Path to a directory containing custom external Checkov checks.</i><br><br><b>--repo-id</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Identifier for the repository, often used with Bridgecrew platform integration.</i><br><br><b>--config-file</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Path to a Checkov configuration file in YAML format.</i><br><br><b>--enable-secrets</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Enable secrets scanning (experimental).</i><br><br><b>--enable-sast</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Enable SAST scanning (experimental).</i><br><br><b>--help (-h)</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Show the help message and exit.</i><br><br>


title: DESCRIPTION
content:
<b>checkov</b> is an open-source static analysis tool designed to scan Infrastructure-as-Code (IaC) files for security misconfigurations, compliance violations, and best practice adherence. It supports a wide range of IaC frameworks including <i>Terraform, CloudFormation, Kubernetes, Azure Resource Manager (ARM), Serverless Framework, Helm charts, Dockerfile, and more</i>. By integrating <b>checkov</b> into CI/CD pipelines, development teams can identify and remediate security risks early in the development lifecycle, preventing insecure configurations from reaching production environments. It provides out-of-the-box policies based on security best practices and compliance standards, and also allows users to define custom policies to enforce specific organizational requirements. The tool outputs scan results in various formats, making it adaptable for different reporting and automation needs.


title: CAVEATS
content:
<b>checkov</b> is <i>not a native Linux command</i> and must be installed separately (e.g., via <b>pip</b>, <b>brew</b>, or Docker). It performs <i>static analysis</i>, meaning it analyzes code at rest and does not detect runtime vulnerabilities or configuration drift. Its effectiveness relies on the comprehensiveness of its built-in policies and the accuracy of custom policies. False positives or negatives can occur, requiring fine-tuning of checks or exclusions.


title: <I>INSTALLATION</I>
content:
<b>checkov</b> can be installed via <b>pip</b> (Python package manager): <code>pip install checkov</code>. Alternatively, it's available via Homebrew on macOS (<code>brew install checkov</code>) or as a Docker image (<code>docker pull bridgecrew/checkov</code>) for easy portability and environment isolation.


title: <I>CUSTOM POLICIES</I>
content:
Users can extend <b>checkov</b>'s capabilities by writing custom checks using Python. These checks are typically placed in a designated directory and referenced using the <b>--external-checks-dir</b> option, allowing organizations to enforce unique security or compliance requirements not covered by built-in policies.


title: <I>CI/CD INTEGRATION</I>
content:
Due to its command-line interface and various output formats, <b>checkov</b> is ideally suited for integration into CI/CD pipelines (e.g., <i>GitHub Actions, GitLab CI/CD, Jenkins, Azure DevOps</i>). This ensures that IaC code is scanned automatically as part of the development workflow, failing builds if critical misconfigurations are detected.


title: HISTORY
content:
<b>checkov</b> was originally developed by <i>Bridgecrew</i>, an IaC security company. Bridgecrew was acquired by <i>Palo Alto Networks</i> in 2021, integrating <b>checkov</b> into their <i>Prisma Cloud</i> platform. Despite the acquisition, <b>checkov</b> remains an active and widely adopted open-source project, continuously maintained by the community and Palo Alto Networks.


title: SEE ALSO
content:
terrascan(1): <i>Another open-source static code analyzer for IaC.</i>, tfsec(1): <i>Security scanner specifically for Terraform code.</i>, kube-linter(1): <i>Static analysis tool for Kubernetes configurations.</i>, yamllint(1): <i>A linter for YAML files.</i>, ansible-lint(1): <i>A linter for Ansible playbooks and roles.</i>


title: PARAMETERS
content:
<b>-a, --all</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Performs a comprehensive set of all available PC health checks.<br><br><b>-c, --cpu</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Focuses diagnostics on CPU status, including load average and temperature.<br><br><b>-m, --memory</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Checks memory utilization, swap usage, and basic memory health.<br><br><b>-d, --disk</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Analyzes disk space usage and reports on S.M.A.R.T. data for drive health.<br><br><b>-n, --network</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Tests network connectivity and reports on active network interfaces.<br><br><b>-t, --temp</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Monitors and displays crucial system temperatures from sensors.<br><br><b>-s, --summary</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides a brief, high-level summary of the PC's health status.<br><br><b>-v, --verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Increases verbosity, showing more detailed diagnostic output.<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message with available options and usage information.<br><br>


title: DESCRIPTION
content:
The <I>checkpc</I> command, though <B>not a standard or widely available utility</B> in most Linux distributions, would conceptually serve as a comprehensive diagnostic tool for assessing the general health and status of a personal computer system. Were it to exist, its primary purpose would be to provide users with a quick and concise overview of critical system components and their operational status.<br><br>This would typically include monitoring CPU load and temperature, analyzing memory utilization and identifying potential issues, checking disk space availability and integrity via S.M.A.R.T. data, and verifying network connectivity. Additionally, a hypothetical <I>checkpc</I> might report on crucial system temperatures and provide insights into the status of essential services. Its design would aim to consolidate various system checks into a single, easy-to-use interface, helping identify performance bottlenecks, hardware malfunctions, or resource exhaustion before they lead to more significant problems. While <I>checkpc</I> itself is not commonly found, the functionalities it implies are crucial for system maintenance and troubleshooting, often achieved through a combination of other specialized Linux commands and utilities.


title: CAVEATS
content:
It is important to note that <B>checkpc is not a standard Linux command</B> included by default in most mainstream distributions like Debian, Ubuntu, Fedora, or RHEL. Its name may occasionally appear in custom scripts, very old or specialized diagnostic tools, or as a hypothetical concept for a PC health checker. Users looking to perform system diagnostics and health checks on Linux should instead rely on a combination of established, standard utilities such as <I>lshw</I>, <I>dmidecode</I>, <I>sensors</I>, <I>smartctl</I>, <I>free</I>, <I>top</I>, and <I>df</I> to gather the necessary information. Creating a comprehensive PC health script often involves combining the output of these individual commands.


title: PARAMETERS
content:
<b><b>--nocolor</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables colored output, which can be useful when redirecting output to a file or for scripts that do not handle ANSI escape codes.<br><br><b><b>--nosync</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prevents <b>checkupdates</b> from syncing the package databases (<I>pacman -Sy</I>). If this option is used, the command will rely on the locally cached databases, which might be outdated. Use with caution if you need the most current update information.<br><br><b><b>--noprogressbar</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables the progress bar during database synchronization. This is often used in scripts or environments where a dynamic progress bar would interfere with logging or parsing.<br><br>


title: DESCRIPTION
content:
The <b>checkupdates</b> command is a utility primarily used on Arch Linux and its derivatives. It allows users to preview available package updates without actually downloading or installing them. This is crucial for maintaining a healthy Arch Linux system, as it adheres to the 'never partial upgrade' philosophy. By running <b>checkupdates</b>, the system's package databases are temporarily synchronized (similar to <I>pacman -Sy</I>), and then a query is performed (similar to <I>pacman -Qu</I>) to display packages that are outdated on the local system compared to the repositories. The command outputs a list of packages along with their old and new versions, making it easy for users to assess the scope of an upcoming upgrade. This capability helps users plan for potential service interruptions, review significant package changes, or simply stay informed about the system's update status before committing to a full system upgrade using <I>pacman -Syu</I>.


title: CAVEATS
content:
<b>checkupdates</b> is specific to Arch Linux and systems using the <b>pacman</b> package manager. While it syncs databases, it does not download or install packages; a full system upgrade (<I>pacman -Syu</I>) is still required to apply updates. Relying solely on <I>--nosync</I> can lead to outdated information if databases haven't been recently synchronized. Always follow <b>checkupdates</b> with a full system upgrade (<I>pacman -Syu</I>) relatively soon after to prevent potential partial upgrade scenarios, especially if external tools or services are querying updated database information.


title: OUTPUT FORMAT
content:
The command typically outputs one line per outdated package, formatted as: <I>packagename old_version -> new_version</I>. This clear format aids in quick assessment of pending updates.


title: ROOT PRIVILEGES
content:
To synchronize package databases (the default behavior without <I>--nosync</I>), <b>checkupdates</b> requires root privileges, usually invoked with <b>sudo</b>. Without these, it will fail to update the databases.


title: SCRIPT AUTOMATION
content:
Due to its safe and non-intrusive nature, <b>checkupdates</b> is frequently used in custom scripts, desktop widgets, and system monitoring tools to display the number of pending updates to the user, without requiring user interaction for an actual upgrade.


title: HISTORY
content:
The <b>checkupdates</b> command is not a core binary of the <b>pacman</b> package manager itself but is part of the <b>pacman-contrib</b> package, which provides a collection of useful helper scripts for <b>pacman</b>. Its development emerged from the Arch Linux community's need for a safe way to preview updates without incurring a 'partial upgrade' state (where package databases are updated but packages are not). Over time, it became an indispensable tool for many Arch Linux users, ensuring a more stable and predictable update process.


title: PARAMETERS
content:
<b><b>-a</b>, <b>--all</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Includes official repository packages in the update list alongside AUR packages.<br><br><b><b>-r</b>, <b>--repo-only</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Alias for <b>--all</b>; also includes official repository packages.<br><br><b><b>-q</b>, <b>--quiet</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppresses informational output, showing only the list of outdated packages.<br><br><b><b>-v</b>, <b>--verbose</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides more detailed output regarding the update check process.<br><br>


title: DESCRIPTION
content:
<i>checkupdates-aur</i> is a utility designed for Arch Linux users to identify pending updates for packages installed from the <b>Arch User Repository (AUR)</b>. Unlike <i>checkupdates</i>, which exclusively checks official repository packages, <i>checkupdates-aur</i> focuses on the user-maintained packages from the AUR.<br><br>This command is invaluable for users who want to review potential updates before initiating a full system upgrade via <i>pacman -Syu</i>. It provides a list of outdated AUR packages, allowing users to assess compatibility, review <b>PKGBUILD</b> changes, or anticipate any manual intervention that might be required during the update process. It does not perform the actual update; it merely lists them, making it a crucial step in a proactive system maintenance workflow.<br><br>Often bundled with AUR helper tools like <i>aurutils</i>, it extends the system's update awareness beyond the official repositories, ensuring a comprehensive view of all potentially outdated software on an Arch system.


title: CAVEATS
content:
<i>checkupdates-aur</i> typically relies on an installed <b>AUR helper</b>, such as <i>aurutils</i>, to function correctly. It serves solely as an informational tool and <b>does not perform any package upgrades</b>. Users must manually initiate updates, often via their chosen AUR helper (e.g., <i>aur sync</i> or <i>yay -Syu</i>) after reviewing the output. Updates to AUR packages may sometimes require manual intervention, such as resolving <i>.pacnew</i> files or recompiling against new dependencies.


title: INTEGRATION WITH UPGRADE WORKFLOW
content:
It is common practice for Arch Linux users to run <i>checkupdates-aur</i> (often combined with <i>checkupdates</i>) before executing a full system upgrade (<i>pacman -Syu</i>). This allows users to review all pending updates, identify any potential conflicts or manual interventions required for AUR packages, and prepare accordingly, leading to a smoother and more controlled upgrade experience.


title: HISTORY
content:
<i>checkupdates-aur</i> emerged from the Arch Linux community's need for a unified way to track updates for both official repository packages and those from the Arch User Repository (AUR). While <i>checkupdates</i> handled official repos, the AUR's growing prominence necessitated a complementary tool. It is not part of the official <i>pacman</i> suite but developed by community members and integrated into various AUR helper projects, notably <i>aurutils</i>, to provide a comprehensive update overview without immediate installation.


title: PARAMETERS
content:
<b>--device=<i>DEVICE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the webcam device path, for example, <i>/dev/video0</i>.<br><br><b>--fullscreen</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts the Cheese application in fullscreen mode.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the version information of Cheese and exits.<br><br><b>--display=<i>DISPLAY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the X display to use for the application.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a general help message with common command-line options.<br><br><b>--help-all</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides a comprehensive list of all available help options.<br><br>


title: DESCRIPTION
content:
Cheese is a user-friendly <i>GNOME</i> application designed for interacting with webcams.<br><br>It provides a simple and intuitive interface to effortlessly capture photos and record videos directly from your webcam. Beyond basic capture, Cheese offers a variety of fun visual effects that can be applied in real-time to your photos and videos, adding a creative touch to your media.<br><br>Its primary focus is on ease of use, making it an ideal tool for quick captures, experimenting with visual styles, or simply checking your webcam functionality within the Linux desktop environment. Cheese integrates seamlessly with the <i>GNOME</i> desktop, providing a straightforward experience for users of all levels.


title: CAVEATS
content:
Cheese is predominantly a graphical user interface (GUI) application, meaning its command-line usage is limited primarily to launching the application with specific initial settings rather than offering extensive terminal-based control.<br><br>It relies on a properly configured and detected webcam with compatible drivers (V4L2 is common on Linux). Its capabilities are centered around capturing and applying effects, not advanced video editing or complex production features.


title: INTEGRATION AND SIMPLICITY
content:
One of the key design philosophies behind Cheese is its seamless integration with the <i>GNOME</i> desktop. It adheres to <i>GNOME</i>'s Human Interface Guidelines, ensuring a consistent and intuitive user experience.<br><br>Its simplicity makes it an excellent choice for users who need basic webcam functionality without the complexity of more advanced multimedia suites.


title: HISTORY
content:
Cheese was developed as part of the <i>GNOME</i> desktop environment project, with its initial release in 2007. It was created to provide a simple, user-friendly, and accessible webcam application for the Linux platform, addressing the need for a straightforward tool to take photos and videos.<br><br>Its development has focused on maintaining ease of use and integrating well with the <i>GNOME</i> ecosystem, becoming a standard utility for many <i>GNOME</i> users.


title: SYNOPSIS
content:
<b>chem</b> <I>subcommand</I> [ <I>options</I> ] [ <I>arguments</I> ]<br><b>chem</b> [ <I>options</I> ] <I>input_file</I> [ <I>output_file</I> ]


title: PARAMETERS
content:
<b><I>subcommand</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the operation to perform. Common subcommands might include <B>convert</B> (for format conversion), <B>info</B> (for displaying molecular information), <B>calc</B> (for calculating properties), or <B>clean</B> (for structural manipulation).<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help information for the command or a specific subcommand.<br><br><b>-v, --version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the version of the <B>chem</B> utility.<br><br><b>-i <I>format</I>, --input-format=<I>format</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Explicitly specifies the input file format (e.g., <I>smi</I>, <I>sdf</I>, <I>mol2</I>, <I>pdb</I>). If omitted, the command attempts to autodetect the format.<br><br><b>-o <I>format</I>, --output-format=<I>format</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Explicitly specifies the output file format. This option is typically used with the <B>convert</B> subcommand or when writing results to a new file.<br><br><b>--add-hydrogens</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Adds implicit hydrogens to the molecular structure, making them explicit. Useful for certain calculations or conversions.<br><br><b>--remove-hydrogens</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Removes explicit hydrogens from the molecular structure, converting them back to implicit where appropriate.<br><br><b>--standardize</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Applies a set of standardization rules to the chemical structure (e.g., normalizing tautomers, representing salts consistently).<br><br><b>-p <I>property</I>, --property=<I>property</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Used with the <B>calc</B> subcommand to specify a molecular property to calculate (e.g., <I>mw</I> for molecular weight, <I>logp</I> for octanol-water partition coefficient, <I>tpsa</I> for topological polar surface area).<br><br><b>-s <I>SMILES_string</I>, --smiles=<I>SMILES_string</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides chemical input directly as a SMILES string, bypassing file input.<br><br><b><I>input_file</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The path to the input chemical file containing structures or data. Required for most operations.<br><br><b><I>output_file</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The path where the output chemical data or results should be written. If omitted, output typically goes to standard output (stdout).<br><br>


title: DESCRIPTION
content:
The <B>chem</B> command, in this conceptual analysis, represents a hypothetical command-line utility designed for basic manipulation and analysis of chemical structures and data within a Linux environment. While not a standard or universally available command in most Linux distributions, its purpose would be to streamline common tasks encountered in computational chemistry, cheminformatics, and drug discovery workflows. <br><br>Such a utility would typically offer functionalities like converting between various chemical file formats (e.g., SMILES, SDF, Mol2, PDB), calculating fundamental molecular properties (e.g., molecular weight, exact mass, logP, TPSA), and performing basic structural modifications (e.g., adding or removing hydrogens, sanitizing structures, generating 2D coordinates). <br><br>Its primary value would lie in enabling quick, scriptable operations on chemical datasets, facilitating automation, batch processing, and integration with other command-line tools. It would serve as a convenient front-end for underlying cheminformatics libraries and toolkits, abstracting complex operations into simple, intuitive commands.


title: CAVEATS
content:
It is crucial to note that <B>chem</B> is <I>not a standard, universally installed Linux command</I>. This analysis describes a conceptual or hypothetical command that aggregates common cheminformatics functionalities. Actual implementations of such features are provided by specialized software packages and libraries like <B>Open Babel</B> (<I>obabel</I> command), <B>RDKit</B> (Python library), <B>ChemAxon</B> tools, or custom scripts utilizing these underlying frameworks. The behavior and exact options of any real <B>chem</B>-named command would depend entirely on its specific development and purpose.


title: TYPICAL USAGE EXAMPLES
content:
Below are some examples of how a conceptual <B>chem</B> command might be used:<br><br><b>1. Convert SDF to SMILES:</b><br><I>chem convert -i sdf -o smi input.sdf output.smi</I><br>or simply:<br><I>chem input.sdf output.smi -o smi</I><br><br><b>2. Calculate Molecular Weight from SMILES:</b><br><I>chem calc --property=mw --smiles="CCO"</I><br><br><b>3. Add Hydrogens and Standardize a Molecule:</b><br><I>chem clean --add-hydrogens --standardize input.mol output_cleaned.mol</I><br><br><b>4. Get Information about a Molecule:</b><br><I>chem info molecule.mol</I>


title: UNDERLYING TECHNOLOGIES
content:
A real-world <B>chem</B> command would likely be a wrapper script or compiled program leveraging powerful open-source cheminformatics libraries such as:<br>- <B>Open Babel</B>: For extensive file format support and basic cheminformatics functionalities.<br>- <B>RDKit</B>: A robust toolkit for cheminformatics, machine learning, and property calculations.<br>- <B>CDK (Chemistry Development Kit)</B>: Another comprehensive Java-based toolkit for cheminformatics.


title: HISTORY
content:
The concept of a unified command-line tool for chemistry operations stems from the long-standing need for efficient data manipulation in computational chemistry. Historically, various tasks were handled by disparate, often specialized, programs from different research groups or software vendors. Tools like <B>Open Babel</B> emerged as comprehensive solutions for chemical file format interconversion and basic property calculation, effectively serving as the de facto 'chem' utility in many contexts. While no single command was formally named <B>chem</B> across Linux distributions, the underlying functionalities have evolved significantly with advancements in cheminformatics libraries and the increasing demand for automation in scientific workflows.


title: PARAMETERS
content:
<b>init [repo]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Initializes</I> chezmoi in your home directory and clones your dotfiles repository. If <I>repo</I> is omitted, it defaults to a common location.<br><br><b>add [path...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Adds</I> files or directories from your home directory to chezmoi's source directory, preparing them for management.<br><br><b>apply</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Applies</I> changes from your source directory to your home directory, synchronizing dotfiles and creating necessary links/files.<br><br><b>diff</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Shows</I> the differences between your source directory and your home directory, indicating what <I>apply</I> would do without making actual changes.<br><br><b>edit [path...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Opens</I> the source file corresponding to a given destination path in your configured editor, allowing you to modify your dotfiles source.<br><br><b>status</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Shows</I> the status of your dotfiles, indicating which are out of sync with your source directory and why.<br><br><b>update</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Pulls</I> changes from your remote dotfiles repository and then <I>applies</I> them, effectively updating your local dotfiles.<br><br><b>doctor</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Checks</I> for common problems and misconfigurations within your chezmoi setup and suggests solutions.<br><br><b>--dry-run</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Simulates</I> the execution of a command without making any actual changes to the filesystem. Useful for previewing.<br><br><b>--verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Enables</I> verbose output, showing more details about what chezmoi is doing during execution.<br><br><b>--force</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><I>Forces</I> the operation, overriding existing files or ignoring warnings that would otherwise prevent the command from executing.<br><br>


title: DESCRIPTION
content:
<b>chezmoi</b> is a powerful and flexible dotfile manager that helps you manage your configuration files across multiple machines. It works by maintaining a source directory (usually version-controlled with Git) containing your desired dotfile state. When you run <I>chezmoi apply</I>, it synchronizes your home directory with this source, creating symlinks, copying files, and even running scripts.<br><br>A key feature is its ability to use Go templates, allowing for machine-specific configurations (e.g., different hostnames, OS types, or user settings). It also supports secrets management by integrating with external password managers. <b>chezmoi</b> prioritizes idempotence, ensuring that <I>apply</I> can be run repeatedly without unintended side effects. It provides excellent <I>diff</I> and <I>status</I> capabilities to preview changes before applying them.


title: CAVEATS
content:
Steep learning curve for advanced features like templating, secrets management, and cross-platform configurations.<br>Initial setup requires careful planning to avoid accidental overwrites of existing files.<br>Can be opinionated about file structures (e.g., dotfiles typically reside in <I>~/.local/share/chezmoi</I> by default).<br>Requires a basic understanding of Git for managing the dotfiles source repository.


title: TEMPLATING
content:
<br><I>chezmoi</I> supports Go's text/template syntax, allowing for dynamic configuration based on host-specific variables (e.g., hostname, OS, user, machine architecture), environment variables, or even the output of external commands. This enables a single source of truth for dotfiles that can adapt to diverse system environments.


title: SECRETS MANAGEMENT
content:
<br>It can integrate with various external password managers (e.g., LastPass CLI, 1Password CLI, Bitwarden CLI, gopass, pass) to securely manage sensitive data within your dotfiles. This prevents secrets from being committed directly to your version control system, enhancing security.


title: IDEMPOTENCE AND SAFETY
content:
<br><I>chezmoi</I> is designed to be idempotent; running <I>chezmoi apply</I> multiple times will consistently result in the same desired state without unintended side effects. It provides robust <I>diff</I> and <I>status</I> commands to preview changes meticulously before applying them, significantly enhancing safety and control over your configuration.


title: HISTORY
content:
<b>chezmoi</b> was created by Tom Payne and first released in 2019. It was designed to address perceived shortcomings in existing dotfile managers, particularly regarding idempotence, cross-platform compatibility, and robust templating. It quickly gained popularity due to its powerful features, active development, and clear focus on safety and reliability, establishing itself as a modern standard for dotfile management.


title: PARAMETERS
content:
<b><b>-f</b>, <b>--full-name</b> <i>NAME</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the user's full name.<br><br><b><b>-r</b>, <b>--room-number</b> <i>NUMBER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the user's office room number.<br><br><b><b>-w</b>, <b>--work-phone</b> <i>NUMBER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the user's work phone number.<br><br><b><b>-h</b>, <b>--home-phone</b> <i>NUMBER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the user's home phone number.<br><br><b><b>-o</b>, <b>--other-info</b> <i>INFO</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets any other additional information.<br><br><b><b>-l</b>, <b>--list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the current finger information for the specified user (or the current user if none is specified).<br><br><b><i>username</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the login name of the user whose GECOS information is to be changed. Only the <i>root</i> user can specify a <i>username</i> other than their own.<br><br>


title: DESCRIPTION
content:
The <b>chfn</b> (change finger information) command is used to modify the GECOS field (also known as the "finger information" field) for a user's entry in the system's password file, typically `<i>/etc/passwd</i>`. This field traditionally stores details such as the user's full name, office room number, office phone number, and home phone number. The information provided via <b>chfn</b> is primarily displayed by the `<i>finger</i>(1)` command, which provides a lookup service for user details on a system. It can also be utilized by various mail clients or other system utilities that require a more descriptive identification of a user beyond their username.<br><br>When executed without options for specific fields, <b>chfn</b> interactively prompts the user for each piece of information (Full Name, Room Number, Work Phone, Home Phone). If a prompt is left blank, the existing value for that field is retained; if the field was previously empty, it remains empty. Users can typically change their own GECOS information without requiring superuser privileges. The `<i>root</i>` user, however, has the ability to change the GECOS information for any user on the system by specifying the target username as an argument. While the `<i>finger</i>` service and its associated information are less prevalent in modern, internet-facing systems due to privacy and security concerns, <b>chfn</b> remains a standard utility for managing this historical user data.


title: CAVEATS
content:
The information set by <b>chfn</b> is stored in the GECOS field of the `<i>/etc/passwd</i>` file. This data is generally readable by all users on the system, which can pose privacy concerns.<br><br>The primary utility that consumes this information, the `<i>finger</i>(1)` service, is often disabled on modern multi-user systems due to these privacy implications and potential information leakage, making the information less useful in practice. Some systems might have stricter security policies or use alternative user management tools that could override or not fully utilize the GECOS field.


title: GECOS FIELD STRUCTURE
content:
The GECOS field, which <b>chfn</b> modifies, is a comma-separated string in the fourth field of an `<i>/etc/passwd</i>` entry. The traditional order for these fields is Full Name, Room Number, Work Phone, Home Phone, and Other Information. <b>chfn</b> is designed to parse and update these specific sub-fields, maintaining the expected structure within the `<i>/etc/passwd</i>` file.


title: HISTORY
content:
The <b>chfn</b> command has roots in early Unix systems, where it was a standard utility for users to update their personal information that could be queried by the `<i>finger</i>(1)` command. It was integral to the `<i>finger</i>` protocol, which provided a simple way to get details about users on a system or network.<br><br>On Linux, <b>chfn</b> is typically provided as part of the `<i>shadow-utils</i>` package (responsible for user and group account management) or sometimes `<i>util-linux</i>`. Its development has largely followed the evolution of Unix-like operating systems, adapting to modern file formats and security practices (e.g., handling `<i>/etc/shadow</i>` for passwords while still modifying `<i>/etc/passwd</i>` for GECOS). While its interactive nature remains, the overall usage has decreased significantly as the `<i>finger</i>` service itself has become less common due to privacy concerns and the move towards more distributed and less directly exposed user information services.


title: SYNOPSIS
content:
<b><code>chgpasswd [OPTIONS]</code></b><br><i>(Input is typically provided via standard input, e.g., <code>echo 'groupname:new_password' | chgpasswd</code>)</i>


title: PARAMETERS
content:
<b>-R, --root CHROOT_DIR</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a different chroot directory to apply password changes within.<br><br><b>STDIN Input</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The command expects input in the format '<i>groupname:new_password</i>' on standard input for each group.<br><br>


title: DESCRIPTION
content:
The <b>chgpasswd</b> command, while not a standard or widely available utility on most modern Linux distributions, would conceptually serve to update group passwords, typically in a batch or non-interactive manner.<br><br>If present, its primary purpose would be to allow system administrators to programmatically change passwords for multiple groups at once, reading group-password pairs from standard input or a specified file. This contrasts with interactive utilities like <b>gpasswd</b>, which is the standard command for managing group passwords and memberships, including changing a single group's password.<br><br>In environments where <b>chgpasswd</b> might exist (e.g., highly specialized systems or older distributions), it would be invaluable for scripting tasks, such as initial system setup, migrations, or automated password rotation policies for group accounts. Its functionality would likely mirror that of <b>chpasswd</b> (for user passwords), but adapted for group contexts.


title: CAVEATS
content:
<b>Non-Standard Command</b>:<br>The most significant caveat is that <b>chgpasswd</b> is <b>not a standard Linux command</b> and is rarely found on modern distributions. The correct and widely available utility for managing group passwords is <b>gpasswd</b>.<br><br><b>Security Implications</b>:<br>If such a command were used, feeding plain-text passwords through standard input or files poses security risks. Care must be taken to secure input data.<br><br><b>Privileges</b>:<br>Changing group passwords typically requires root privileges.


title: WHY GPASSWD IS PREFERRED
content:
For managing group passwords and membership, <b>gpasswd</b> is the universally accepted and comprehensive utility. It supports changing group passwords interactively, adding/removing members, and setting administrative passwords for group management. <b>chgpasswd</b> would only focus on batch password changes, making it less versatile.


title: TYPICAL BATCH USE CASE (HYPOTHETICAL)
content:
In scenarios where <b>chgpasswd</b> might be implemented, its primary use would be in scripts. For example, to set initial passwords for many groups during system deployment, or to comply with security policies requiring regular, automated password resets for service-related groups.


title: HISTORY
content:
While not a commonly adopted standalone utility, the concept behind <b>chgpasswd</b> mirrors the need for batch operations in system administration. Its hypothetical existence would likely stem from a desire to extend the functionality of <b>chpasswd</b> (for users) to group management. Historically, the <b>gpasswd</b> command has evolved to handle both interactive and programmatic group password changes, effectively absorbing the functionality that a separate <b>chgpasswd</b> might offer, thus making a dedicated command largely redundant in mainstream Linux distributions.


title: SYNOPSIS
content:
<b>chgrp</b> [<i>OPTION</i>]... <i>GROUP FILE</i>...<br><b>chgrp</b> [<i>OPTION</i>]... <b>--reference</b>=<i>RFILE FILE</i>...


title: PARAMETERS
content:
<b>-c, --changes</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Verbose</i>; like <b>--verbose</b> but only report when a change is made.<br><br><b>-f, --silent, --quiet</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Suppress</i> most error messages.<br><br><b>-v, --verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Explain</i> what is being done.<br><br><b>-R, --recursive</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Operate</i> on files and directories recursively.<br><br><b>-h, --no-dereference</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Affect</i> symbolic links themselves instead of the files they reference.<br><br><b>--dereference</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Affect</i> the files referenced by symbolic links (this is the default).<br><br><b>--reference=RFILE</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Use</i> the group of <i>RFILE</i> instead of specifying a <i>GROUP</i> name or ID.<br><br><b>GROUP</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The <i>new group</i> name or numeric Group ID (GID) for the specified files.<br><br><b>FILE...</b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more <i>files or directories</i> whose group ownership is to be changed.<br><br>


title: DESCRIPTION
content:
<i>chgrp</i>, short for "change group", is a fundamental Linux command used to modify the group ownership of files and directories. In a multi-user environment, permissions and access control are critical. Files and directories typically have an owner (a user) and an owning group. The <i>chgrp</i> command allows system administrators or file owners to reassign a file's group to a different existing group. This is essential for managing access rights, as file permissions can be set differently for the owner, the owning group, and others. For instance, you might want to give read-write access to a specific team (represented by a group) for a set of project files, while limiting access for everyone else. By changing the group ownership of these files to the team's group, and then adjusting file permissions with <i>chmod</i>, you can achieve the desired access policy. The command supports recursive operations, allowing entire directory trees to have their group ownership altered efficiently. Proper use of <i>chgrp</i> is vital for maintaining a secure and well-organized file system.


title: CAVEATS
content:
Only the <i>root</i> user or the current owner of a file can change its group. Furthermore, to change a file's group, the owner must also be a member of the <i>new group</i>. On GNU systems, <i>root</i> can change it to any group. Changing group ownership does <b>not</b> automatically alter file permissions (e.g., read, write, execute bits); this requires a separate command like <i>chmod</i>. The specified <i>GROUP</i> must exist in the system's group database (e.g., <i>/etc/group</i>), unless a numeric GID is used.


title: <B>USING GID INSTEAD OF GROUP NAME</B>
content:
Instead of a symbolic <i>group name</i>, you can specify the new group using its <i>numeric Group ID (GID)</i>. This can be useful in environments where group names might be inconsistent or when working with automated scripts. For example, <b>chgrp 5000 myfile.txt</b> would assign the file to the group with GID 5000.


title: <B>IMPACT ON SETGID BIT</B>
content:
If a file has the <i>setgid</i> bit set, changing its group ownership might remove this bit for security reasons, especially if the owner is not <i>root</i>. For directories, the <i>setgid</i> bit ensures that newly created files and subdirectories within it inherit the group of the parent directory. Changing the group of a directory with <i>chgrp</i> while the <i>setgid</i> bit is active will cause new files to be created with the new group.


title: HISTORY
content:
The <i>chgrp</i> command has been an integral part of Unix-like operating systems since their early development. It was created to facilitate multi-user environments where different users and groups require distinct access privileges to files and resources. Its functionality is standardized by POSIX (Portable Operating System Interface), ensuring consistent behavior across various Unix-like systems. The GNU core utilities implementation of <i>chgrp</i>, commonly found on Linux distributions, provides additional features and options, such as the <b>--reference</b> flag, which enhance its flexibility and usability.


title: PARAMETERS
content:
<b>-f, --frequency <Hz></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the frequency of the chirp in Hertz (Hz). Defaults to a predefined value.<br><br><b>-d, --duration <ms></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the duration of the chirp in milliseconds (ms). Defaults to a short burst (e.g., 50ms).<br><br><b>-v, --volume <0-100></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Adjusts the playback volume, where 0 is mute and 100 is maximum. This option might require appropriate permissions or audio system configuration.<br><br><b>-o, --output <device_or_file></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Directs the chirp output to a specific audio device (e.g., <I>/dev/dsp</I>) or a WAV file path (e.g., <I>output.wav</I>).<br><br><b>-q, --quiet</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppresses all informational and warning messages from the command, playing only the chirp sound.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows version information and exits.<br><br>


title: DESCRIPTION
content:
Please note: The <B>chirpw</B> command is <I>not a standard, widely recognized Linux utility</I>. This analysis is based on a hypothetical command designed to emit a short, distinct auditory signal or 'chirp'. If it were to exist, <B>chirpw</B> would likely provide a simple way to generate an audible notification or alert from the command line. This could be useful for shell scripts to signal completion, errors, or other events without requiring complex audio playback tools. Users could potentially customize the frequency, duration, and volume of the chirp, making it adaptable for various notification purposes or even basic debugging scenarios where an audio cue is preferred over visual output.<br><br>The command would abstract away the complexities of direct audio device interaction, offering a straightforward interface for triggering a quick sound event. Its design would prioritize simplicity and efficiency, ideal for integration into automated tasks or for immediate, transient feedback.


title: CAVEATS
content:
The <B>chirpw</B> command is <I>not a standard component</I> of most Linux distributions. This description is hypothetical. If such a command were implemented, it would likely require appropriate audio drivers (e.g., ALSA or PulseAudio) and permissions to access audio devices. Its availability and exact behavior would depend entirely on a specific implementation or user-defined script.


title: USAGE EXAMPLES (HYPOTHETICAL)
content:
<B>1. Basic Chirp:</B><br><I>chirpw</I><br>Plays a short chirp with default settings.<br><br><B>2. Custom Frequency and Duration:</B><br><I>chirpw --frequency 1000 --duration 200</I><br>Plays a 1000 Hz chirp for 200 milliseconds.<br><br><B>3. High Volume Alert:</B><br><I>chirpw -v 90 -f 2000 -d 150</I><br>Emits a loud, high-pitched, short alert.<br><br><B>4. Chirp in a Script for Notification:</B><br><I>#!/bin/bash</I><br><I>echo "Starting long task..."</I><br><I># Hypothetical long_running_script execution</I><br><I>if long_running_script; then</I><br><I>&nbsp;&nbsp;chirpw -f 500 -d 100 -v 80</I><br><I>&nbsp;&nbsp;echo "Task completed successfully!"</I><br><I>else</I><br><I>&nbsp;&nbsp;chirpw -f 1500 -d 300 -v 100</I><br><I>&nbsp;&nbsp;echo "Task failed! Check logs."</I><br><I>fi</I><br>


title: HISTORY
content:
As <B>chirpw</B> is <I>not a standard or widely recognized Linux command</I>, there is no documented development history or significant usage evolution within the public Linux ecosystem. Any existing instance of <B>chirpw</B> would be a custom script, alias, or part of a very specialized, non-mainstream package. Its conceptual origin would likely stem from the need for simple, direct audible feedback in terminal environments, similar to the functionality provided by the <B>beep</B> command for PC speakers, but potentially with more modern audio system integration.


title: SEE ALSO
content:
<B>aplay</B>(1): A simple command-line sound file player from ALSA utilities, capable of playing various audio formats., <B>beep</B>(1): A program that makes the PC speaker beep. Often used for simple audible notifications in scripts., <B>play</B>(1): Part of the SoX (Sound eXchange) utility, a highly versatile command-line audio player and recorder., <B>mplayer</B>(1): A general-purpose media player that can also play audio files and streams, often used for simple audio playback in scripts.


title: SYNOPSIS
content:
<b>chisel server</b> <I>[OPTIONS]</I><br><b>chisel client</b> <I>[OPTIONS]</I> <I>&lt;SERVER_ADDRESS&gt;</I> <I>[REMOTES...]</I><br><br><I>&lt;SERVER_ADDRESS&gt;</I>: The address of the <b>chisel</b> server (e.g., <I>localhost:8080</I>, <I>example.com:80</I>).<br><I>[REMOTES...]</I>: One or more remote forwarding rules, similar to SSH's <b>-L</b>, <b>-R</b>, or <b>-D</b> options. Format examples: <I>L:local_port:remote_host:remote_port</I>, <I>R:remote_port:local_host:local_port</I>, <I>SOCKS</I>, <I>http-proxy:local_port</I>.


title: PARAMETERS
content:
<b><b>-p</b>, <b>--port</b> <I>&lt;port&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the listening port for the server or the server port for the client.<br><br><b><b>--reverse</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables reverse tunneling, allowing remote clients to connect to services on the client's network.<br><br><b><b>--socks5</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Activates a SOCKS5 proxy on the specified local port (client) or on the server side to be used by clients (server).<br><br><b><b>--http</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Activates an HTTP proxy on the specified local port (client) or on the server side to be used by clients (server).<br><br><b><b>--auth</b> <I>&lt;user:pass&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets basic authentication credentials for client connections or server-side authentication.<br><br><b><b>--proxy</b> <I>&lt;proxy_addr&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies an upstream HTTP or SOCKS proxy for the client to connect through.<br><br><b><b>--log-level</b> <I>&lt;level&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the logging verbosity (e.g., <I>debug</I>, <I>info</I>, <I>warn</I>, <I>error</I>).<br><br><b><b>--keep-alive</b> <I>&lt;duration&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the interval for sending keep-alive packets to prevent connection timeouts (e.g., <I>30s</I>).<br><br><b><b>--bind</b> <I>&lt;addr&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the network interface address for the server to listen on.<br><br><b><b>--max-sess</b> <I>&lt;count&gt;</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Limits the maximum number of concurrent client sessions the server will accept.<br><br>


title: DESCRIPTION
content:
<b>chisel</b> is a high-performance, cross-platform TCP/UDP tunnel, often referred to as a "fast SSH-like tunnel". It operates in two primary modes: <b>server</b> and <b>client</b>. Its main purpose is to establish secure and efficient network connections, typically used for bypassing firewalls, exposing internal services to the outside world, or creating secure back-channels through restrictive networks.<br><br>Unlike traditional SSH tunnels, <b>chisel</b> is designed for speed and simplicity, making it ideal for situations where a full SSH daemon is not available or desired, or when higher throughput is required. It can tunnel a variety of protocols, including HTTP proxies, SOCKS5 proxies, and raw TCP/UDP connections. <b>chisel</b> supports both <I>local forwarding</I> (connecting a local port to a remote service) and <I>reverse forwarding</I> (connecting a remote port to a local service), similar to SSH's <b>-L</b> and <b>-R</b> options. It uses a custom protocol over HTTP or raw TCP for data transmission, with optional basic authentication for security. Its small binary size and single-file distribution make it highly portable.


title: CAVEATS
content:
<b>chisel</b> is not a full-fledged VPN solution and does not encrypt all network traffic by default; it only encrypts the tunnel itself. While it provides basic authentication, it lacks advanced security features like public-key authentication or granular access controls found in SSH. Performance can be influenced by network latency and bandwidth, though it's optimized for speed. Misuse can lead to security vulnerabilities if not properly configured, especially when exposing internal services to the public internet without proper access restrictions.


title: <B>CLIENT MODE EXAMPLES</B>
content:
To create a local SOCKS5 proxy on port 1080 connected to a <I>chisel</I> server at <I>example.com:8080</I>: <br> `<b>chisel client --socks5 example.com:8080</b>` <br><br> To forward local port 8000 to remote host <I>internal-db:5432</I> via the server: <br> `<b>chisel client example.com:8080 8000:internal-db:5432</b>`


title: <B>SERVER MODE EXAMPLES</B>
content:
To start a <I>chisel</I> server listening on port 8080: <br> `<b>chisel server --port 8080</b>` <br><br> To start a server with authentication and enable reverse tunneling: <br> `<b>chisel server --port 8080 --auth user:pass --reverse</b>`


title: <B>REVERSE TUNNELING</B>
content:
Reverse tunneling with <I>chisel</I> allows services on the client's network to be exposed to the server's network. The server must be started with the <I>--reverse</I> flag. Clients can then establish reverse tunnels using the <I>R:remote_port:local_host:local_port</I> syntax. For example, to expose the client's local web server on port 80 to the server's port 8080: <br> `<b>chisel client --reverse example.com:8080 R:8080:localhost:80</b>`


title: HISTORY
content:
<b>chisel</b> was created by <I>jpillora</I> and first released around 2014-2015. Its development aimed to address the need for a faster and simpler alternative to SSH for TCP/UDP tunneling, especially in environments where SSH might be blocked or overkill. It gained popularity for its ease of use, cross-platform compatibility (being written in Go), and its ability to quickly set up proxies and bypass firewalls. It continues to be actively maintained and used for its specific niche in network utility.


title: SYNOPSIS
content:
<b>chkconfig</b> [--list [<I>name</I>]]<br><b>chkconfig</b> [--add <I>name</I>]<br><b>chkconfig</b> [--del <I>name</I>]<br><b>chkconfig</b> [--level <I>levels</I>] <I>name</I> [<I>on</I>|<I>off</I>|<I>reset</I>]<br><b>chkconfig</b> [--override <I>name</I> [<I>on</I>|<I>off</I>]]<br><b>chkconfig</b> [--query <I>name</I>]


title: PARAMETERS
content:
<b>--list [<I>name</I>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists the current runlevel configuration for services. If <I>name</I> is provided, lists configuration for that specific service.<br><br><b>--add <I>name</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Adds a new service for management by chkconfig. It reads default runlevel information from the service's init script.<br><br><b>--del <I>name</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Removes a service from chkconfig management, deleting its runlevel symlinks.<br><br><b>--level <I>levels</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the runlevels (0-6, S) on which the operation (on/off/reset) should apply. E.g., '35' for runlevels 3 and 5.<br><br><b><I>name</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The name of the service (corresponding to its script name in /etc/init.d/).<br><br><b><I>on</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables the service at the specified (or default) runlevels, creating 'S' links.<br><br><b><I>off</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables the service at the specified (or default) runlevels, creating 'K' links.<br><br><b><I>reset</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Resets the service configuration to its default runlevel settings as defined in the init script.<br><br><b>--override <I>name</I> [<I>on</I>|<I>off</I>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Permanently overrides a service's default runlevel configuration, preventing it from being changed by subsequent 'on', 'off', or 'reset' actions unless explicitly specified. Useful for system upgrades that might reset configurations.<br><br><b>--query <I>name</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Queries the runlevel configuration for a single service without the full list output.<br><br>


title: DESCRIPTION
content:
The <b>chkconfig</b> command is a command-line utility used on Linux systems, primarily those utilizing the System V (SysV) init system, to manage the services that are started or stopped during system boot at various runlevels. It provides a convenient interface for querying, adding, deleting, and setting the runlevel configuration for services. <br><br>Historically, SysV init scripts located in <i>/etc/init.d/</i> are linked into runlevel-specific directories like <i>/etc/rc0.d/</i>, <i>/etc/rc1.d/</i>, ..., <i>/etc/rc6.d/</i>. <b>chkconfig</b> automates the creation and removal of these symbolic links (e.g., <i>SNNname</i> for start, <i>KNNname</i> for kill) in the appropriate <i>/etc/rcX.d/</i> directories, based on the service's default runlevel configuration found within the script itself. <br><br>While many modern Linux distributions have transitioned to <i>systemd</i> as their primary init system, where <i>systemctl</i> is the preferred command for managing services, <b>chkconfig</b> might still be present for compatibility or for managing legacy services that haven't been converted to <i>systemd</i> units. Its main purpose is to configure the <i>boot-time behavior</i> of services, not to start or stop them immediately; for that, commands like <i>service</i> or <i>systemctl</i> are used.


title: CAVEATS
content:
The <b>chkconfig</b> command is primarily designed for systems using the traditional System V init process. <br><br>On modern Linux distributions that have adopted <i>systemd</i> (such as recent Fedora, CentOS/RHEL, Debian, Ubuntu versions), <b>chkconfig</b>'s direct functionality is largely superseded by the <i>systemctl</i> command. While <b>chkconfig</b> might still be available for backward compatibility, its use for new configurations or systemd-native services is discouraged. <br><br>It requires root privileges to modify service configurations. <br><br><b>chkconfig</b> configures <i>boot-time behavior</i>; it does not start or stop services immediately. To control a service's current running state, use commands like <i>service</i> or <i>systemctl</i>.


title: RUNLEVELS EXPLAINED
content:
In System V init, a runlevel is a state of the operating system that defines which services are running. Common runlevels include: <br><i><b>0</b></i>: Halt (system shutdown)<br><i><b>1</b></i>: Single-user mode (maintenance)<br><i><b>2</b></i>: Multi-user, without NFS (user-defined)<br><i><b>3</b></i>: Full multi-user mode (text mode)<br><i><b>4</b></i>: Unused (user-defined)<br><i><b>5</b></i>: Full multi-user mode with graphical display (X11)<br><i><b>6</b></i>: Reboot (system restart)<br><i><b>S</b></i> (or <i><b>s</b></i>): Single-user mode<br><b>chkconfig</b> allows you to specify which services start or stop when the system enters or exits these runlevels.


title: INTERACTION WITH INIT SCRIPTS
content:
For <b>chkconfig</b> to manage a service, the service's init script (e.g., <i>/etc/init.d/httpd</i>) must contain specific LSB (Linux Standard Base) compliance headers. These headers define metadata such as the service's default start/kill priorities and the runlevels at which it should be started by default. <b>chkconfig</b> parses these headers to determine how to configure the service when using the <i>--add</i> or <i>reset</i> options.


title: HISTORY
content:
<b>chkconfig</b> originated within the Red Hat Linux ecosystem, being an integral part of its System V init implementation. It was developed to simplify the management of runlevel configurations for services, providing a user-friendly interface compared to manual manipulation of symbolic links in <i>/etc/rcX.d/</i> directories. For many years, it was a staple utility on Red Hat Enterprise Linux, Fedora, CentOS, and other derivatives. Its prominence began to wane with the widespread adoption of <i>systemd</i>, which introduced a new paradigm for service management and superseded many of the functions traditionally handled by <b>chkconfig</b>. Despite this, it remains a valuable tool for maintaining older systems or specific environments that still rely on SysV init.


title: SYNOPSIS
content:
The `chkdupexe` command is an <I>internal test</I> executed by the `<b>chkrootkit</b>` utility. It is <I>not</I> designed for direct user invocation.<br><br>Users interact with `<b>chkrootkit</b>` which then performs the `chkdupexe` check as part of its routine.<br><br>To initiate the check performed by `chkdupexe`, you would run `<b>chkrootkit</b>` itself:<br> `<b>chkrootkit</b> [<I>options</I>]


title: PARAMETERS
content:
<b>-x</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Skipping Tests</I>. Some versions of `<b>chkrootkit</b>` allow specifying tests to skip. While not directly a parameter for `chkdupexe`, you might use `<b>chkrootkit -x chkdupexe</b>` (or similar syntax if supported by the `<b>chkrootkit</b>` version) to exclude this particular check.<br><br><b>-v</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Verbose Output</I>. When `<b>chkrootkit</b>` is run with `<b>-v</b>`, the output from internal tests like `chkdupexe` might be more detailed.<br><br><b>-q</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Quiet Output</I>. Suppresses most output from `<b>chkrootkit</b>`, showing only critical warnings related to all tests including `chkdupexe`.<br><br>


title: DESCRIPTION
content:
The `chkdupexe` command is an internal component or test within the `<b>chkrootkit</b>` (Check Rootkit) utility. Its primary function is to scan the filesystem for signs of duplicate executable files. This check is crucial for detecting rootkits or other malicious software that might attempt to hide their presence by creating copies of legitimate system binaries (often with slight modifications) or by creating hard links to disguise their true location. The test looks for executable files that share identical inode numbers (indicating hard links) or identical content, but reside in different paths. It is <I>not</I> a standalone command meant for direct user execution; instead, it is invoked automatically as part of a comprehensive system integrity check when `<b>chkrootkit</b>` is run. Its findings are integrated into `<b>chkrootkit</b>`'s overall report, alerting the user to potential compromises.


title: CAVEATS
content:
<I>Not Standalone</I>: `chkdupexe` is an internal script/test and cannot be run independently from `<b>chkrootkit</b>`.<br><br><I>False Positives</I>: It may report legitimate duplicate executables (e.g., hard links created by package managers, or different versions/paths of the same binary used for specific purposes) as suspicious. Manual investigation is often required to confirm if a reported duplicate is malicious.<br><br><I>Limited Scope</I>: It only checks for duplicate <I>executable</I> files, not other types of files or processes.


title: ROLE IN ROOTKIT DETECTION
content:
The `chkdupexe` test helps identify a specific type of rootkit activity where attackers replace or duplicate system binaries (like `<b>ls</b>`, `<b>ps</b>`, `<b>netstat</b>`) with malicious versions to hide their processes, files, or network connections. By looking for unexpected duplicate executables or executables with mismatched checksums/inodes in different locations, it flags potential compromises.


title: HOW IT WORKS (SIMPLIFIED)
content:
The test typically scans common executable paths (`/bin`, `/usr/bin`, `/sbin`, etc.) and potentially other user-defined paths. For each executable found, it might compare its inode number with others (for hard links) or calculate a hash/checksum of its content. If identical content or inode is found at different paths, it's flagged as a potential duplicate, indicating a possible rootkit.


title: HISTORY
content:
The `chkdupexe` test has been an integral part of the `<b>chkrootkit</b>` suite since its early development. `<b>chkrootkit</b>` was initially released in 1997 by Nelson Murilo and is continuously maintained to adapt to new rootkit techniques. The inclusion of `chkdupexe` reflects the common rootkit tactic of hiding malicious binaries by duplicating or replacing legitimate system executables.


title: PARAMETERS
content:
<b><b>-q</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Quiet mode.</i> Suppresses the printing of file and directory names being checked, only reporting errors.<br><br><b><b>-s</b> <i>server</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Specify server.</i> Checks the font paths of a given font server, specified as `[host]:port`, instead of the locally running X server's configuration.<br><br><b><b>-c</b> <i>cache_dir</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Check cache directory.</i> Verifies the integrity of `fonts.cache-1` files within the specified `cache_dir`.<br><br>


title: DESCRIPTION
content:
<i><b>chkfont</b></i> is a utility designed to verify the correctness and integrity of font configurations within the X Window System. It primarily checks the font paths specified for an X server or a dedicated font server (<i>xfs</i>) to ensure they are valid directories and contain necessary font index files (<i>fonts.dir</i>).<br><br>Additionally, it can check the validity of <i>fonts.cache-1</i> files which store font properties for faster access. This command helps diagnose issues related to missing or incorrectly configured fonts that prevent X applications from finding and rendering text correctly. It was a crucial tool for troubleshooting font issues in environments relying on traditional X11 font server setups.


title: CAVEATS
content:
<i><b>chkfont</b></i> is largely considered a legacy utility. Its relevance has significantly diminished in modern Linux distributions where font management is primarily handled by the <i>fontconfig</i> library and its associated tools (<i>fc-cache</i>, <i>font-manager</i>). It is not present in many contemporary systems and is primarily useful for troubleshooting X11 font server (<i>xfs</i>) setups or very old X.Org configurations.


title: LEGACY FONT MANAGEMENT IN X11
content:
Before <i>fontconfig</i> became standard, X applications often located fonts by querying the X server for its configured font paths. These paths pointed to directories containing font files and their associated <i>fonts.dir</i> index files. <i><b>chkfont</b></i> played a role in ensuring these explicit paths were correctly set up and accessible, vital for displaying text in graphical applications. The transition to <i>fontconfig</i> simplified font discovery by abstracting the underlying font locations and providing a more dynamic caching mechanism.


title: HISTORY
content:
<i><b>chkfont</b></i> originated as part of the XFree86 project and was later integrated into the X.Org Foundation's distribution of the X Window System utilities. Its development and usage peaked during an era when X servers relied heavily on explicitly defined font paths and dedicated font servers (<i>xfs</i>). With the advent and widespread adoption of <i>fontconfig</i> (around early 2000s), which offers a more flexible and robust mechanism for font discovery and rendering, the direct reliance on and troubleshooting needs for <i><b>chkfont</b></i> have considerably declined. It represents an older paradigm of font management in Unix-like systems.


title: SYNOPSIS
content:
<b>chmem</b> is not a standard Linux command. No general synopsis or usage syntax exists for typical Linux environments. Attempts to execute it will usually result in a "command not found" error.


title: DESCRIPTION
content:
The command "<b>chmem</b>" is <I>not</I> a standard utility found in typical Linux distributions. Unlike commands like <b>chmod</b> or <b>chown</b>, there is no widely recognized or documented "chmem" command for changing memory characteristics or allocations. It's possible that "chmem" might refer to a highly specialized, proprietary, or custom script in a very specific environment, or it could be a typo for another command.<br><br>In standard Linux, memory management and resource allocation are handled through a variety of mechanisms: process-specific resource limits (e.g., set by <b>ulimit</b>), kernel parameters configurable via <b>sysctl</b>, direct memory allocation by applications through system calls (like <I>mmap</I>, <I>brk</I>), and tools for viewing memory statistics (like <b>free</b>, <b>top</b>, <b>vmstat</b>). There isn't a single command designed to "change memory" in a generic sense across the system or for arbitrary processes.


title: CAVEATS
content:
The command <b>chmem</b> is <I>not</I> a standard component of Linux operating systems. If encountered, it likely refers to a custom script, an extremely niche tool from an obscure distribution, or a command from another Unix-like system (e.g., AIX) that is not part of the Linux ecosystem. Users attempting to run <b>chmem</b> on a typical Linux installation will receive an error such as "<b>bash: chmem: command not found</b>". Memory management in Linux is granular and uses various distinct tools and kernel interfaces rather than a single 'change memory' command.


title: LINUX MEMORY MANAGEMENT OVERVIEW
content:
In Linux, memory is managed by the kernel's virtual memory manager (VMM). Applications request memory using system calls like <I>mmap()</I> or <I>brk()</I>. Resource limits, including memory, can be set per-user or per-process using <B>ulimit</B> (shell builtin) or system-wide via <B>cgroup</B>s (control groups). Shared memory, for inter-process communication, is typically managed via POSIX shared memory (<I>shm_open</I>, <I>shm_unlink</I>) or System V IPC shared memory (<I>shmget</I>, <I>shmat</I>, <I>shmctl</I>), not a generic 'change memory' command.


title: HISTORY
content:
The name "chmem" naturally suggests "change memory." While not a standard Linux command, functionality related to changing memory allocations or shared memory segments has existed under similar names or specific contexts in other Unix-like operating systems (e.g., AIX, where a <b>chmem</b> command exists for modifying shared memory segment sizes). In the Linux world, such functionalities are typically managed through more specialized commands, kernel interfaces, or programming constructs, rather than a single, general "chmem" utility. Its absence from standard Linux reflects the architectural differences in how memory and process resources are managed compared to some older Unix implementations.


title: SYNOPSIS
content:
<i>chmod</i> [<i>OPTION</i>]... <i>MODE</i>[,<i>MODE</i>]... <i>FILE</i>...<br><i>chmod</i> [<i>OPTION</i>]... <i>OCTAL-MODE FILE</i>...<br><i>chmod</i> [<i>OPTION</i>]... --reference=<i>RFILE FILE</i>...


title: PARAMETERS
content:
<b>-c, --changes</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Like verbose, but report only when a change is made.<br><br><b>-f, --silent, --quiet</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppress most error messages.<br><br><b>-v, --verbose</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output a diagnostic for every file processed.<br><br><b>--no-preserve-root</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not treat '/' specially (default).<br><br><b>--preserve-root</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Fail to operate recursively on '/'.<br><br><b>--reference=RFILE</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Use RFILE's mode instead of MODE values.<br><br><b>-R, --recursive</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Change files and directories recursively.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display this help and exit.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output version information and exit.<br><br>


title: DESCRIPTION
content:
The <i>chmod</i> command is a fundamental Linux utility used to change access permissions of file system objects (files and directories). Permissions dictate who can read, write, or execute a file, and who can traverse or list a directory. There are three primary types of permissions: <i>read</i> (r), <i>write</i> (w), and <i>execute</i> (x). These permissions can be assigned to three distinct categories of users: the <i>owner</i> of the file (u), the <i>group</i> associated with the file (g), and <i>others</i> (o).<br><br><i>chmod</i> supports two main modes for specifying permissions: <i>symbolic mode</i> and <i>octal (numeric) mode</i>. In symbolic mode, you use characters to add (+), remove (-), or set (=) permissions for specific user categories (e.g., u+x, g-w, o=rwx). Octal mode uses a three or four-digit octal number, where each digit represents the permissions for owner, group, and others, respectively. Each permission type has a numeric value: read (4), write (2), and execute (1). These values are summed to form the octal digit (e.g., 7 = rwx (4+2+1), 5 = rx (4+1)). A fourth leading digit can specify special permissions like SUID, SGID, or the sticky bit.


title: CAVEATS
content:
Using <i>chmod -R</i> on the root directory (<i>/</i>) can render a system unbootable or unusable if not done with extreme caution. Be mindful of special permissions (SUID, SGID, sticky bit) as they have security implications. The execute bit for directories grants permission to traverse or search the directory, not necessarily to list its contents (which requires read permission).


title: SYMBOLIC MODE EXPLAINED
content:
Symbolic mode uses a combination of user types (u, g, o, a for all), operators (+ to add, - to remove, = to set exactly), and permission types (r, w, x, s for SUID/SGID, t for sticky bit). For example, <i>chmod u+x,go-w myfile</i> adds execute permission for the owner and removes write permission for group and others.


title: OCTAL MODE EXPLAINED
content:
Octal mode uses a numerical representation of permissions. Each digit in the three-digit number corresponds to owner, group, and others. The values are: read (4), write (2), execute (1). These sum up for each category. For example, <i>755</i> means owner has rwx (4+2+1=7), group has rx (4+1=5), and others have rx (4+1=5). A four-digit number includes special permissions: 4000 for SUID, 2000 for SGID, 1000 for sticky bit (e.g., <i>2755</i> for SGID on a directory).


title: SPECIAL PERMISSIONS
content:
The <i>setuid (SUID)</i> bit (4000) on an executable allows it to run with the privileges of its owner. The <i>setgid (SGID)</i> bit (2000) on an executable runs it with the privileges of its group; on a directory, new files/subdirectories inherit the parent's group ownership. The <i>sticky bit</i> (1000) on a directory prevents users from deleting or renaming files in that directory unless they own the file or the directory, even if they have write permission for the directory itself (common for <i>/tmp</i>).


title: HISTORY
content:
The concept of file permissions and the <i>chmod</i> command have been integral to Unix-like operating systems since their inception in the late 1960s and early 1970s. It was a foundational component of the security and multi-user capabilities designed into Unix, allowing administrators and users to control access to their files and programs effectively. Its syntax and core functionality have remained remarkably consistent over decades, underscoring its fundamental role in system administration.


title: PARAMETERS
content:
<b><i>samfile</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The path to the Windows SAM file. This is usually <i>/path/to/windows/system32/config/SAM</i> on a mounted Windows partition.<br><br><b>-i</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Interactive mode. Presents a menu for user selection and actions.<br><br><b>-l</b><br>&nbsp;&nbsp;&nbsp;&nbsp;List all local users in the SAM file.<br><br><b>-u <i><username></i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a particular username to operate on. Used with other options.<br><br><b>-N</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Do not change password (used for other operations like clearing, enabling, disabling).<br><br><b>-E</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Clear (blank) the password for the specified user.<br><br><b>-d</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disable (lock out) the specified user account.<br><br><b>-e</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enable the specified user account (if disabled).<br><br><b>-v</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Verbose output, showing more details about operations.<br><br><b>-L</b><br>&nbsp;&nbsp;&nbsp;&nbsp;List all user accounts with their Relative ID (RID), including disabled accounts.<br><br><b>-r</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Remove the password for a user account (same as -E).<br><br><b>-c</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Change password for a user. Requires interactive input.<br><br><b>-s <i><system_file></i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the path to the SYSTEM hive file (required for decryption).<br><br><b>-C <i><security_file></i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the path to the SECURITY hive file (required for decryption).<br><br>


title: DESCRIPTION
content:
The <b>chntpw</b> command is a utility designed for offline modification of the Security Account Manager (SAM) database file in Windows NT/2000/XP/Vista/7/8/10 operating systems. Its primary purpose is to reset or clear local Windows user passwords, enable or disable user accounts, and promote/demote users between administrator and standard user groups. It works by directly accessing and modifying the SAM file, which typically resides in <i>C:\Windows\System32\config\SAM</i> on a Windows installation. Because it operates offline, it bypasses the need for the user to be logged into the Windows operating system, making it an invaluable tool for forgotten passwords or managing user accounts on unbootable systems. Users typically run <b>chntpw</b> from a Linux live environment (e.g., a bootable USB drive or CD) after mounting the Windows partition containing the SAM file. It is a powerful tool for system recovery and administration, but requires careful use due to its direct interaction with critical system files.


title: CAVEATS
content:
<b>Offline Access Required:</b> <b>chntpw</b> operates only when the Windows system is offline and its disk can be mounted.<br><b>Data Corruption Risk:</b> Improper use or power failure during operation can corrupt the SAM file, potentially rendering Windows unbootable. Always back up critical files (SAM, SYSTEM, SECURITY hives) before use.<br><b>Encrypted Drives:</b> It cannot access or modify SAM files on encrypted drives (e.g., BitLocker, VeraCrypt) unless the drive is first unlocked and mounted.<br><b>Local Accounts Only:</b> <b>chntpw</b> only affects local Windows accounts and cannot reset passwords for domain accounts.<br><b>Password Hashes:</b> It clears or resets the password; it does not reveal the original password.<br><b>UAC and Modern Windows:</b> On Windows 7 and newer, UAC (User Account Control) might behave unexpectedly after a password reset, sometimes requiring a temporary password or further configuration to restore full functionality.


title: LOCATING SAM FILE
content:
The SAM file is typically found at <i>C:\Windows\System32\config\SAM</i> on a Windows installation. You will also often need the SYSTEM and SECURITY hive files (<i>C:\Windows\System32\config\SYSTEM</i> and <i>C:\Windows\System32\config\SECURITY</i>) for <b>chntpw</b> to function correctly, especially for decrypting the SAM file's contents.


title: USAGE WITH LIVE ENVIRONMENTS
content:
To use <b>chntpw</b>, you typically boot your computer from a Linux live CD/USB (e.g., Ubuntu, Kali Linux, SystemRescueCd). Once in the live environment, you mount the Windows partition (e.g., <i>/dev/sda1</i> to <i>/mnt/windows</i>) and then specify the full path to the SAM file, like <i>/mnt/windows/Windows/System32/config/SAM</i>.


title: BACKUP RECOMMENDED
content:
Before any operation, it is highly recommended to create backups of the SAM, SYSTEM, and SECURITY hive files. Copying them to a safe location (e.g., another drive or USB) can prevent data loss in case of corruption.


title: HISTORY
content:
Developed by Petter Nordahl-Hagen, <b>chntpw</b> was created as a robust solution for a common problem: forgotten Windows passwords. Its development focused on providing a direct, offline method to manipulate the Windows SAM database, making it a staple in IT troubleshooting and recovery toolkits. Despite the evolution of Windows security, its core functionality remains vital for scenarios where traditional password recovery methods are unavailable or impractical.


title: PARAMETERS
content:
<b><b>-p</b>, <b>--protect</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Protects the specified process from being OOM-killed. This sets the <b>oom_score_adj</b> to <b>-1000</b>, the lowest possible value, making the process highly unlikely to be chosen by the OOM killer.<br><br><b><b>-n</b> <i>&lt;value&gt;</i>, <b>--oom-score-adj</b> <i>&lt;value&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the <b>oom_score_adj</b> for the process to the specified <i>&lt;value&gt;</i>. The valid range for this value is from <b>-1000</b> (most protected) to <b>1000</b> (most vulnerable). Positive values increase vulnerability, negative values decrease it.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a brief help message and exits.<br><br><b><b>-V</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information for the <i>choom</i> utility and exits.<br><br>


title: DESCRIPTION
content:
<i>choom</i> is a Linux command-line utility used to modify a process's Out-Of-Memory (OOM) killer score adjustment (<b>oom_score_adj</b>) or to entirely protect a specific process and its children from being OOM-killed. The Linux kernel's OOM killer is invoked when the system runs out of memory. It selects and terminates processes based on their OOM score, a dynamic value indicating memory consumption and criticality. A higher OOM score means a process is more likely to be killed.<br><br><i>choom</i> allows administrators and users to influence this behavior, making a process either more or less likely to be killed by the OOM killer. Using the <b>-p</b> (protect) option sets the <b>oom_score_adj</b> to its lowest possible value (-1000), effectively making the process almost immune to the OOM killer. This is crucial for critical services that must remain running even under severe memory pressure.


title: CAVEATS
content:
Using <i>choom</i>, especially with the <b>-p</b> option or a very low <b>oom_score_adj</b> value, requires careful consideration. Protecting a process from the OOM killer means that if the system runs critically low on memory, other, potentially more critical processes might be killed instead, or the system could experience a hard lock-up if no processes can be killed to free memory.<br><br>Modifying <b>oom_score_adj</b> for processes not owned by the current user, or for system-wide processes, typically requires <b>root</b> privileges. Not all Linux distributions include <i>choom</i> by default; it is often part of the <i>util-linux</i> package.


title: THE LINUX OOM KILLER
content:
The Out-Of-Memory (OOM) killer is a crucial component of the Linux kernel's memory management. Its purpose is to prevent system crashes when physical memory and swap space are exhausted. When activated, it identifies and terminates one or more processes to reclaim memory, allowing the system to continue operating. The selection algorithm aims to kill processes that consume significant memory and are considered less critical, based on various heuristics including the process's <b>oom_score</b>.


title: UNDERSTANDING <B>OOM_SCORE_ADJ</B>
content:
The <b>oom_score_adj</b> value acts as an adjustment to a process's calculated <b>oom_score</b>. This file, located at <b>/proc/<i>&lt;pid&gt;</i>/oom_score_adj</b>, allows administrators to make a process more or less attractive to the OOM killer. A value of <b>0</b> (the default) means no adjustment. A negative value (e.g., <b>-500</b>) reduces the process's effective OOM score, making it less likely to be killed. A positive value (e.g., <b>500</b>) increases the score, making it more vulnerable. The extreme value of <b>-1000</b> (used by <i>choom</i>'s <b>-p</b> option) effectively ensures the process will not be killed by the OOM killer unless there are absolutely no other options or severe kernel misconfiguration.


title: HISTORY
content:
<i>choom</i> is a relatively recent addition to the suite of Linux command-line utilities, typically distributed as part of the <i>util-linux</i> package since versions around 2.27. It provides a user-friendly wrapper for the underlying <b>/proc/[pid]/oom_score_adj</b> kernel interface, which has existed for a longer period. Its development aimed to simplify and standardize the method for adjusting OOM killer behavior for processes, making it more accessible for system administrators to manage application resilience during memory pressure situations.


title: SEE ALSO
content:
prlimit(1), nice(1), renice(1), /proc/[pid]/oom_score_adj, /proc/[pid]/oom_score, /proc/sys/vm/oom_kill_allocating_task


title: PARAMETERS
content:
<b><b>-i</b>, <b>--ignore-case</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Ignores case</I> when filtering or matching items.<br><br><b><b>-p PROMPT</b>, <b>--prompt=PROMPT</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the <I>custom prompt string</I> to display to the user. Defaults to "Choose: ".<br><br><b><b>-r</b>, <b>--regex</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Interprets the user's input as a <I>regular expression</I> for filtering, rather than a simple substring match.<br><br><b><b>-s</b>, <b>--show-items</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the <I>raw values</I> of the items alongside their numbered names (if applicable).<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the <I>version information</I> of the <b>choose</b> utility and exits.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a <I>brief help message</I> detailing usage and options, then exits.<br><br>


title: DESCRIPTION
content:
The <b>choose</b> command is a compact yet powerful command-line utility designed for <I>interactive item selection</I> from a given list.<br><br>It primarily serves as a convenient tool for shell scripting, enabling users to present a list of options and receive a single, chosen item back. Input can be provided either as <I>command-line arguments</I> or via <I>standard input</I> (e.g., from a pipe).<br><br>Upon execution, <b>choose</b> displays the available items, often numerically or with their raw values, along with a customizable prompt. Users can then type part of an item's name or an index to <I>filter</I> the list dynamically. Once an item is selected (typically by pressing Enter), the chosen item is printed to <I>standard output</I>, making it easily usable in subsequent commands or script variables.<br><br>Its simplicity makes it ideal for quick, interactive decisions within automated workflows or daily command-line tasks where a full-fledged fuzzy finder might be overkill. It effectively bridges the gap between static scripting and dynamic user interaction.


title: CAVEATS
content:
The <b>choose</b> command is <I>not a standard utility</I> universally available on all Linux distributions by default; it often requires installation via a specific package (e.g., 'linux-choose').<br><br>While useful for simple selection, it <I>lacks advanced features</I> like fuzzy matching or complex UI elements found in more sophisticated interactive tools such as fzf or percol.


title: INPUT METHODS
content:
The <b>choose</b> command can receive its list of items in two primary ways:<br>1. <I>Direct arguments</I>: `choose item1 item2 "item with space"`<br>2. <I>Standard input (pipe)</I>: `ls -1 | choose` or `cat items.txt | choose`


title: BASIC USAGE EXAMPLE
content:
To select a file from the current directory interactively:<br>`selected_file=$(ls -1 | choose -p "Pick a file: ")`<br>`echo "You chose: $selected_file"`


title: HISTORY
content:
The <b>choose</b> command emerged as a lean, focused utility to address the common need for <I>simple interactive selection</I> in shell scripts and command-line environments. Unlike core GNU utilities, its development is typically maintained by individual projects or smaller utility collections, aiming to provide a lightweight alternative to more feature-rich but potentially heavier interactive tools. Its prevalence varies across distributions, reflecting its role as a specialized helper rather than a foundational system command.


title: SYNOPSIS
content:
<b>chown</b> [<i>OPTION</i>]... <i>OWNER</i>[<i>:[GROUP]</i>] <i>FILE</i>...<br><b>chown</b> [<i>OPTION</i>]... <i>--reference=RFILE FILE</i>...


title: PARAMETERS
content:
<b><i>OWNER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The new owner for the specified files. Can be a username or numeric UID.<br><br><b><i>GROUP</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The new group for the specified files. Can be a group name or numeric GID. Preceded by a colon (<i>:</i>) after the owner.<br><br><b><i>FILE...</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more files or directories whose ownership will be changed.<br><br><b><b>-R</b>, <b>--recursive</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Recursively change ownership of directories and their contents.</i><br><br><b><b>-v</b>, <b>--verbose</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Output a diagnostic for every file processed.</i><br><br><b><b>-c</b>, <b>--changes</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Like --verbose, but report only when a change is made.</i><br><br><b><b>-f</b>, <b>--silent</b>, <b>--quiet</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Suppress most error messages.</i><br><br><b><b>--from=</b><i>CURRENT_OWNER</i>[<i>:CURRENT_GROUP</i>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Change the owner/group only if the current owner/group matches this specification.</i><br><br><b><b>--no-preserve-root</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Do not treat '/' specially when operating recursively. By default, chown refuses to operate on the root directory recursively.</i><br><br><b><b>--reference=</b><i>RFILE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Use the owner and group of the specified <I>RFILE</I> instead of explicit <I>OWNER</I> and <I>GROUP</I> arguments.</i><br><br>


title: DESCRIPTION
content:
The <b>chown</b> command is used to change the user and/or group ownership of specified files or directories. It is a fundamental command for managing file system permissions and security in Linux and Unix-like operating systems.<br><br>By assigning specific users and groups as owners, administrators can control who has access to read, write, or execute files and directories. The command accepts either a user name (e.g., <i>john</i>) or a numeric user ID (UID), and optionally a group name (e.g., <i>staff</i>) or a numeric group ID (GID). If only a user is specified, their primary group may implicitly become the new group owner, or the existing group owner may remain. If a group is specified after a colon (e.g., <i>john:staff</i>), both user and group ownership are changed simultaneously.<br><br><b>chown</b> is crucial for setting up proper access controls, especially when managing shared resources, web servers, or application data, ensuring that processes run with appropriate privileges and that sensitive information is protected.


title: CAVEATS
content:
To change the ownership of a file or directory, you typically need to be the superuser (root) or have appropriate capabilities. Ordinary users can only change the group ownership of a file if they are the owner of the file and a member of the target group.<br><br>When changing the owner of an executable file, the set-user-ID (SUID) bit will be cleared for security reasons. Similarly, the set-group-ID (SGID) bit will be cleared if the group is changed and the file is executable.<br><br><b>chown</b>, by default, follows symbolic links and changes the ownership of the file the link points to, not the symbolic link itself. To change the ownership of the symbolic link itself (if supported by the filesystem), the <i>lchown</i> system call would be used, but the <i>chown</i> command does not typically expose an option for this behavior directly in GNU coreutils.


title: USAGE WITH NUMERIC IDS
content:
Instead of user and group names, you can also specify numeric UIDs and GIDs. For example, <i>chown 1000:1001 file.txt</i> would change the owner to user ID 1000 and group ID 1001. This is particularly useful in environments where user/group names might not be consistently mapped or when dealing with NFS mounts where UIDs/GIDs are paramount.


title: HISTORY
content:
The <b>chown</b> command has been a staple of Unix-like operating systems since their early days. It is part of the POSIX standard, ensuring its consistent behavior across various Unix and Linux distributions. Its implementation is usually provided by GNU coreutils on Linux systems, reflecting its fundamental role in system administration and security.


title: SYNOPSIS
content:
<b>chpasswd</b> [<i>OPTIONS</i>] <br><i>(Input is typically provided via standard input, e.g., 'username:password' lines.)</i>


title: PARAMETERS
content:
<b><b>-e</b>, <b>--encrypted</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Tells <i>chpasswd</i> that the passwords provided in the input are already encrypted. This means the input format should be 'username:encrypted_password' where the encrypted password is a valid crypt(3) hash string.<br><br><b><b>-c</b>, <b>--crypt-method</b> <i>METHOD</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the crypt method to use for hashing passwords. Valid methods typically include <i>SHA512</i>, <i>SHA256</i>, <i>BCRYPT</i>, <i>MD5</i>, etc., depending on the system's crypt library support. This option overrides the default system hashing method.<br><br><b><b>-m</b>, <b>--md5</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Uses MD5 as the encryption method for passwords. This option is generally considered deprecated in favor of <b>--crypt-method MD5</b> as it specifies a weaker hashing algorithm compared to modern standards like SHA512 or BCRYPT.<br><br><b><b>-R</b>, <b>--root</b> <i>CHROOT_DIR</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Applies the password changes in a specified chroot environment. This is useful for managing accounts on a system image or a recovery partition without actually booting into it.<br><br>


title: DESCRIPTION
content:
<i>chpasswd</i> is a utility designed to update multiple user passwords from a list. It reads username:password pairs, one per line, from standard input or a specified file. This command is particularly useful for system administrators who need to manage a large number of user accounts, automate user provisioning, or migrate user data. Unlike the <i>passwd</i> command which interactively prompts for a single password, <i>chpasswd</i> operates in a non-interactive batch mode, making it ideal for use within scripts or automated processes. It handles the secure hashing of passwords internally, using the system's default hashing algorithm unless otherwise specified. Due to its nature of modifying sensitive system files, <i>chpasswd</i> requires superuser (root) privileges to execute.


title: CAVEATS
content:
<ul><li><b>Security</b>: The input stream or file containing username:password pairs often contains cleartext passwords (unless <b>-e</b> is used). Ensure these inputs are highly secured and promptly deleted after use.</li><li><b>Permissions</b>: This command requires superuser (root) privileges to modify the <i>/etc/shadow</i> file.</li><li><b>Input Format</b>: It strictly expects 'username:password' or 'username:encrypted_password' (with <b>-e</b>) pairs, one per line. Any deviation can lead to errors.</li><li><b>Error Handling</b>: <i>chpasswd</i> typically stops processing on the first error encountered, which might mean only a subset of passwords are updated if an error occurs early in the input.</li><li><b>Hashing Algorithm</b>: By default, it uses the system's configured password hashing algorithm (often defined in <i>/etc/login.defs</i> or <i>/etc/default/useradd</i>). Consider specifying a strong method with <b>-c</b> if the system default is weak.</li></ul>


title: INPUT DATA FORMAT
content:
The standard input for <i>chpasswd</i> must consist of lines in the format '<i>username:password</i>'. Each line represents a single user and their new password. If the <b>-e</b> (encrypted) option is used, the format becomes '<i>username:encrypted_password</i>', where the 'encrypted_password' is an already hashed password string compatible with <i>crypt(3)</i>. Leading or trailing whitespace on a line can cause errors.


title: PASSWORD HASHING MECHANISM
content:
When plain-text passwords are provided (without <b>-e</b>), <i>chpasswd</i> uses the <i>crypt(3)</i> library function to hash them before storing them in <i>/etc/shadow</i>. The specific hashing algorithm used defaults to the system's configured method, typically found in <i>/etc/login.defs</i> (e.g., <i>ENCRYPT_METHOD</i>) or <i>/etc/default/useradd</i>. This can be explicitly overridden using the <b>--crypt-method</b> option to ensure strong, modern hashing algorithms are employed.


title: HISTORY
content:
<i>chpasswd</i> is a part of the <i>shadow-utils</i> package, which provides a suite of tools for managing user and group accounts on Linux systems. Its development was driven by the need for efficient, automated password management in environments with large numbers of users, such as enterprise systems, educational institutions, or cloud deployments. It addresses the limitation of interactive password change tools by enabling non-interactive, batch processing, which is crucial for scripting and system provisioning tasks that became common with the rise of automated infrastructure management.


title: SYNOPSIS
content:
<code>chroma <B>[OPTIONS]</B> <B>[SUBCOMMAND]</B> <B>[ARGS]...</B></code><br><br><i>Examples:</i><br><code>chroma --version</code><br><code>chroma run --port 8000</code><br><code>chroma migrate</code>


title: PARAMETERS
content:
<b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the installed version of the ChromaDB client.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a help message for the `chroma` command or a specific subcommand.<br><br><b>[SUBCOMMAND]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a particular operation to perform (e.g., `run`, `migrate`). Specific options and arguments apply to each subcommand.<br><br>


title: DESCRIPTION
content:
The `chroma` command-line utility is an entry point for interacting with <I>ChromaDB</I>, an open-source, AI-native embedding database. It is <B>not a standard Linux command</B> found pre-installed on most distributions. Instead, it's typically installed by users via Python's package manager, `pip`, as part of the `chromadb` library. Its primary purpose is to manage and operate a ChromaDB instance, facilitating tasks such as starting the database server, executing schema migrations, and checking the installed version.<br><br>Unlike traditional single-purpose Linux commands, `chroma` predominantly functions as a dispatcher for various <I>subcommands</I>, each performing a specific operation related to the database. This modular approach allows for a flexible and extensible interface for database administration and development workflows. It bridges the gap between programmatic interaction with ChromaDB and direct command-line control for common administrative tasks.


title: CAVEATS
content:
The `chroma` command is <B>not a core component</B> of typical Linux operating systems. It must be explicitly installed, usually via `pip install chromadb`. Its functionality is entirely dependent on the ChromaDB project and serves as its command-line interface, not a general-purpose system utility. Users should consult the official ChromaDB documentation for the most up-to-date information on subcommands and their specific options.


title: COMMON SUBCOMMANDS
content:
While `chroma` itself has limited direct options, its power lies in its subcommands:<br><ul><li><I><b>run</b></I>: Starts the ChromaDB server instance, typically used for local development or deployment. Accepts various options for configuration (e.g., `--host`, `--port`).<br></li><li><I><b>migrate</b></I>: Executes pending database schema migrations, essential for updating an existing ChromaDB instance to a newer version.<br></li><li><I><b>shell</b></I>: (If applicable in future versions) Provides an interactive shell for direct database interaction.</li></ul>


title: INSTALLATION
content:
The `chroma` command is made available after installing the `chromadb` Python package. This is typically done using `pip`, the Python package installer:<br><br><code><I>pip install chromadb</I></code><br><br>After installation, the `chroma` executable will be available in your system's PATH, assuming Python's script directory is included.


title: HISTORY
content:
The `chroma` CLI tool evolved as an integral part of the <I>ChromaDB project</I>, which was developed to address the burgeoning need for efficient storage and retrieval of vector embeddings in modern AI applications, particularly those leveraging Large Language Models (LLMs). Conceived as an open-source, developer-friendly embedding database, ChromaDB aimed to simplify the infrastructure layer for AI developers. The `chroma` command-line interface was introduced to provide a direct, convenient method for managing ChromaDB instances, from initial setup and server orchestration to database migrations and version checks, reflecting the project's commitment to ease of use and accessibility. Its development parallels the rapid growth of the AI embedding space since the early 2020s.


title: PARAMETERS
content:
<b><i>URL</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Opens the specified URL in a new tab or window.<br><br><b><b>--incognito</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Launches the browser in incognito (private browsing) mode, not saving browsing history, cookies, or site data.<br><br><b><b>--headless</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Runs Chromium in headless mode, without a graphical user interface, primarily used for automated testing or server-side rendering.<br><br><b><b>--app=</b><i>URL</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Opens the specified URL as a standalone web application, without browser UI elements like address bar or tabs.<br><br><b><b>--new-window</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces the specified URL to open in a new browser window, even if a running instance exists.<br><br><b><b>--new-tab</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces the specified URL to open in a new tab within an existing window.<br><br><b><b>--user-data-dir=</b><i>path</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the directory where user profile data (history, bookmarks, settings) is stored. Useful for portable installations or multiple profiles.<br><br><b><b>--profile-directory=</b><i>name</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the profile to use, relative to the user data directory. E.g., 'Profile 1'.<br><br><b><b>--disable-gpu</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Disables GPU hardware acceleration, which can sometimes resolve rendering issues or save resources.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints the Chromium version information and exits.<br><br><b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a list of available command-line options.<br><br>


title: DESCRIPTION
content:
<i><b>chromium</b></i> is the open-source web browser project that forms the foundation for Google Chrome and many other browsers. On Linux, the <i><b>chromium</b></i> command typically launches the Chromium web browser, allowing users to browse the internet, access web applications, and develop web content. It provides a modern, standards-compliant rendering engine (Blink) and a powerful JavaScript engine (V8).<br><br>While sharing much of its codebase with Google Chrome, <i><b>chromium</b></i> generally lacks proprietary components such as built-in PDF viewer, Flash player, and certain media codecs that are licensed by Google for Chrome. It often receives updates more frequently and directly from the open-source project. Users can specify URLs as arguments to open them directly in the browser, or use various command-line options to control its behavior, such as opening in incognito mode, running in headless mode for scripting, or managing user profiles. It's a popular choice for those preferring an open-source browser experience while benefiting from the speed and modern capabilities of the underlying Chromium engine.


title: CAVEATS
content:
<i><b>chromium</b></i>, especially without the `--no-sandbox` flag (which should be avoided for security reasons), can be resource-intensive, particularly with many tabs or complex web applications. Updates are managed by the respective Linux distribution's package manager, so the update cycle might differ from Google Chrome. Users may need to install additional packages for full media codec support or proprietary features sometimes found in Chrome.


title: DEFAULT BROWSER INTEGRATION
content:
On many Linux systems, <i><b>chromium</b></i> can be set as the default web browser, allowing it to open URLs from other applications via tools like <b>xdg-open</b>.


title: DEVELOPMENT AND DEBUGGING
content:
<i><b>chromium</b></i> offers extensive developer tools, accessible via the F12 key or Ctrl+Shift+I, for inspecting web pages, debugging JavaScript, and analyzing network activity. It's a powerful environment for web developers.


title: HISTORY
content:
The <i><b>Chromium</b></i> project was launched by Google in 2008 as the open-source foundation for its Chrome browser. Its primary goal was to build a fast, secure, and stable web browser. The command-line utility for launching the browser has evolved alongside the project, maintaining compatibility with core web standards and introducing new features. Its development is community-driven and continuous, with frequent updates incorporating new web technologies and security patches, making it a living, evolving project that directly influences the web browsing experience for millions globally.


title: PARAMETERS
content:
<b>command</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The command to be executed by <I>chronic</I>.<br><br><b>[arg...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Optional arguments to be passed to the command.<br><br>


title: DESCRIPTION
content:
The <I>chronic</I> command executes a given command and only displays its standard output and standard error if the command fails (i.e., returns a a non-zero exit status) or if it produces <I>any</I> output. If the command succeeds and produces no output, <I>chronic</I> suppresses all output. This utility is particularly useful in automated scripts, especially <I>cron</I> jobs, where you typically only want to be notified if something goes wrong or if there's important information to convey. By wrapping commands with <I>chronic</I>, system administrators can avoid receiving email notifications for routine, successful, and silent tasks, thus reducing inbox clutter and making it easier to spot actual issues. It acts as a filter, allowing silent success and verbose failure.


title: CAVEATS
content:
If the wrapped command produces output but exits successfully (status 0), <I>chronic</I> will still print the output. It only suppresses output if <B>both</B> conditions are met: success <B>and</B> no output. <br> <I>chronic</I> is primarily designed for non-interactive, automated tasks and may not behave as expected with interactive commands.


title: EXIT STATUS
content:
The exit status of <I>chronic</I> itself is the exit status of the <I>command</I> it runs. This allows scripts to directly check the success or failure of the wrapped command, even when using <I>chronic</I>.


title: USE IN CRON
content:
One of its primary and most beneficial use cases is within <I>cron</I> entries. For example, instead of a simple `0 * * * * /usr/local/bin/backup.sh`, you might use `0 * * * * chronic /usr/local/bin/backup.sh`. This ensures that only failures or explicit output from the backup script will generate email notifications, significantly reducing inbox clutter.


title: HISTORY
content:
<I>chronic</I> is a utility part of the <I>moreutils</I> package, a collection of small, useful Unix utilities. The package was created by Joey Hess, and <I>chronic</I> has been a fundamental component since its early days, specifically designed to address the common problem of excessive email notifications from cron jobs for successful, silent operations.


title: SYNOPSIS
content:
<b>chronyc</b> [<i>options</i>] [<i>command</i> [<i>arguments</i> ...]]<br><b>chronyc</b> [<i>options</i>] [<i>hosts</i> ...] <i>command</i> [<i>arguments</i> ...]


title: PARAMETERS
content:
<b>-h <I>host</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the host to connect to. Can be an IP address or hostname.<br><br><b>-p <I>password</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides the authentication password for remote control.<br><br><b>-n</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Don't resolve host names for NTP sources when displaying information.<br><br><b>-m</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Allows specifying multiple chronyd instances (hosts) on the command line in non-interactive mode.<br><br><b>-q</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suppresses informational messages, showing only command output or errors.<br><br><b>-t <I>timeout</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the command timeout in seconds for communication with chronyd.<br><br><b>-i</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces chronyc into interactive mode, even if commands are specified on the command line.<br><br><b>-d</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces chronyc into non-interactive mode, even if no commands are specified on the command line.<br><br><b>-a <I>addr</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Binds chronyc to a specific local address when communicating with chronyd.<br><br>


title: DESCRIPTION
content:
<b>chronyc</b> is the command-line interface for <b>chronyd</b>, the <b>NTP</b> (Network Time Protocol) client and server. It allows users to monitor <b>chronyd</b>'s performance, query its current state, and make runtime configuration changes. <b>chronyc</b> can be used to display information about <b>NTP</b> sources, check the synchronization status of the system clock, adjust <b>NTP</b> tracking parameters, and perform immediate clock adjustments. It communicates with the <b>chronyd</b> daemon, typically via a Unix domain socket for local connections or a network connection for remote control. <b>chronyc</b> supports both interactive and non-interactive modes, making it versatile for scripting and manual administration tasks. It is an essential tool for managing time synchronization on Linux systems using <b>chrony</b>.


title: CAVEATS
content:
Local commands requiring configuration changes or system clock adjustments (e.g., <b>makestep</b>, <b>burst</b>) often require <b>chronyc</b> to be run as root or with appropriate permissions (e.g., membership in the chrony group, or the <b>chronyd</b> process configured to allow unprivileged local control).<br>Remote control requires <b>chronyd</b> to be explicitly configured to allow commands from the client's IP address (using the <b>CMDSPEC</b> directive in <b>chrony.conf</b>) and, for security, should utilize a shared secret for authentication via the <b>-p</b> option.<br>Misconfiguration of <b>chrony.conf</b> or incorrect use of <b>chronyc</b> commands can lead to incorrect system time, which can impact system stability and security.


title: INTERACTIVE VS. NON-INTERACTIVE MODE
content:
<b>chronyc</b> can be run interactively by simply typing <b>chronyc</b> at the command line, which provides a prompt (<b>chronyc></b>) for entering commands. In non-interactive mode, commands are passed directly as arguments, making it suitable for scripts (e.g., <b>chronyc sources</b>).


title: COMMONLY USED COMMANDS
content:
Some frequently used <b>chronyc</b> commands include:<br>- <b>sources</b>: Displays information about the currently configured <b>NTP</b> sources.<br>- <b>tracking</b>: Shows detailed information about the system's time synchronization status.<br>- <b>sourcestats</b>: Provides statistics about each <b>NTP</b> source.<br>- <b>makestep</b>: Forces <b>chronyd</b> to immediately step the system clock to the correct time.<br>- <b>burst <I>count</I></b>: Tells <b>chronyd</b> to perform a burst of <b>NTP</b> requests for faster initial synchronization.<br>- <b>rtc</b>: Displays or adjusts information about the Real Time Clock (RTC).<br>- <b>activity</b>: Shows the number of NTP servers currently online/offline.


title: AUTHENTICATION
content:
For security, especially when controlling <b>chronyd</b> remotely, <b>chronyc</b> supports authentication using a shared secret. This secret is defined in <b>chrony.conf</b> and provided to <b>chronyc</b> via the <b>-p</b> option. Without proper authentication, remote commands may be rejected by <b>chronyd</b>.


title: HISTORY
content:
The <b>chrony</b> project, including <b>chronyc</b>, was initiated by Richard P. C. Quirk with the goal of creating a robust and accurate implementation of the <b>NTP</b> protocol. It was designed to be more suitable than <b>ntpd</b> for systems that are frequently disconnected, have unreliable network access, or are virtual machines where timekeeping can be challenging. <b>chronyc</b> has been an integral part of this project, evolving alongside <b>chronyd</b> to provide comprehensive control and monitoring capabilities for the daemon's advanced features. Its development has focused on efficiency, accuracy, and providing immediate feedback on time synchronization status.


title: PARAMETERS
content:
<b><i>NEWROOT</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the path to the directory that will serve as the new root (/) for the executed command and its descendants. This directory must exist and contain the necessary binaries and libraries for the command to run.<br><br><b>[<i>COMMAND</i>...]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;An optional argument specifying the command and its arguments to execute within the <b>chroot</b> environment. If no command is provided, <b>chroot</b> will attempt to run the shell specified by the <i>SHELL</i> environment variable, or default to <i>/bin/sh</i> if <i>SHELL</i> is not set or its value is not found.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information and exits.<br><br>


title: DESCRIPTION
content:
The <b>chroot</b> command in Linux stands for "change root" and is used to change the apparent root directory for the current running process and its children. This means that a program executed within a <b>chroot</b> environment will perceive the specified <i>NEWROOT</i> directory as the system's root (/).<br><br>This utility provides a basic form of process isolation, often referred to as a "chroot jail" or "chroot environment." Its primary uses include system recovery and maintenance (e.g., repairing a broken bootloader), building software packages in a controlled environment, running older or different distributions, and providing a rudimentary sandbox for applications. While it offers a degree of isolation by restricting file system access to a subset of the actual file system, it's crucial to understand that it does not create a new kernel or provide true virtualization. Processes inside the <b>chroot</b> still share the host system's kernel and resources.


title: CAVEATS
content:
While <b>chroot</b> offers file system isolation, it is <i>not</i> a robust security mechanism for sandboxing untrusted applications. Key limitations include:<br><b>- Kernel Sharing:</b> Processes within a <b>chroot</b> environment share the host system's kernel. A root user inside the <b>chroot</b> can still perform operations like mounting/unmounting file systems, loading kernel modules, or accessing raw devices, which could compromise the host system.<br><b>- Escaping:</b> Experienced attackers or malicious processes with root privileges inside a <b>chroot</b> might be able to escape the jail, for instance, by using nested <b>chroot</b> calls or specific system calls.<br><b>- Resource Isolation:</b> <b>chroot</b> does not isolate other system resources like network interfaces, process IDs (PIDs), or inter-process communication (IPC).<br><b>- Dependency Management:</b> The <i>NEWROOT</i> directory must contain all necessary binaries, libraries, device files (e.g., <i>/dev/null</i>, <i>/dev/urandom</i>), and configuration files that the executed <i>COMMAND</i> and its dependencies require. This often involves copying or bind-mounting these files into the new root, which can be complex.<br><b>- Privilege Requirement:</b> Only the <i>root</i> user can execute the <b>chroot</b> command.


title: TYPICAL USE CASES
content:
<b>chroot</b> is commonly used for:<br><b>- System Recovery:</b> Booting from a live CD/USB and <b>chroot</b>ing into the installed system to repair broken packages, modify configuration files, or reset passwords.<br><b>- Software Compilation:</b> Building software in a clean, isolated environment to ensure consistent dependencies and prevent interference with the host system.<br><b>- Security Auditing:</b> Running untrusted applications in a somewhat isolated environment, though it's not a full security sandbox.<br><b>- Multi-arch Development:</b> Setting up environments for different CPU architectures (e.g., ARM development on an x86 machine) by populating the <i>NEWROOT</i> with the appropriate binaries.


title: PREPARING A CHROOT ENVIRONMENT
content:
For a command to run successfully inside a <b>chroot</b>, the <i>NEWROOT</i> directory must be self-contained. This typically involves:<br><b>- Core Binaries:</b> Copying essential binaries like <i>/bin/sh</i>, <i>/bin/ls</i>, <i>/bin/cat</i>, etc., and their required shared libraries (often found in <i>/lib</i>, <i>/lib64</i>, <i>/usr/lib</i>). The <b>ldd</b> command can help identify library dependencies.<br><b>- Device Files:</b> Creating or bind-mounting necessary device files (e.g., <i>mknod /dev/null c 1 3</i> or <i>mount --bind /dev /newroot/dev</i>).<br><b>- Configuration Files:</b> Copying relevant configuration files (e.g., <i>/etc/resolv.conf</i> for DNS).<br><b>- Mount Points:</b> For certain operations, mounting virtual filesystems like <i>/proc</i> and <i>/sys</i> inside the <b>chroot</b> (e.g., <i>mount --bind /proc /newroot/proc</i>) might be necessary.


title: HISTORY
content:
The underlying <b>chroot</b> system call has a long history, first appearing in Version 7 Unix in 1979. It was primarily designed for system administration tasks, such as creating isolated environments for compiling software or recovering a broken system. The <b>chroot</b> <i>command-line utility</i> provides a user-friendly wrapper around this system call, making it accessible to system administrators. While its core functionality remains unchanged, its role has evolved. It laid some groundwork for more advanced containerization technologies like Docker and LXC, which build upon similar isolation principles but offer more comprehensive and secure sandboxing by leveraging Linux kernel namespaces and cgroups.


title: SYNOPSIS
content:
<b>chrt</b> [<I>options</I>] [<I>priority</I>] <I>command</I> [<I>arguments</I>...]<br><b>chrt</b> [<I>options</I>] -p <I>PID</I>


title: PARAMETERS
content:
<b>-p, --pid <PID></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Operate on an existing process identified by its Process ID (PID) instead of starting a new command. When used, the command and arguments should be omitted.<br><br><b>-f, --fifo</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the scheduling policy to <b>SCHED_FIFO</b> (First-In, First-Out). This policy does not use time slicing; a process runs until it yields or blocks.<br><br><b>-r, --rr</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the scheduling policy to <b>SCHED_RR</b> (Round-Robin). This policy uses a time quantum for fair distribution among processes of the same priority.<br><br><b>-o, --other</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the scheduling policy to <b>SCHED_OTHER</b> (default time-sharing). Real-time priority is ignored; <i>nice</i> value applies.<br><br><b>-b, --batch</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the scheduling policy to <b>SCHED_BATCH</b>, intended for CPU-bound batch jobs that should run at a lower priority than <b>SCHED_OTHER</b> processes.<br><br><b>-i, --idle</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the scheduling policy to <b>SCHED_IDLE</b>, for very low priority tasks that run only when no other process is runnable on the CPU.<br><br><b>-a, --all-tasks</b><br>&nbsp;&nbsp;&nbsp;&nbsp;When operating on an existing PID, apply the scheduling changes to all tasks (threads) belonging to that process.<br><br><b>-m, --max</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display the maximum valid real-time priority (typically 99) supported by the system for <b>SCHED_FIFO</b> and <b>SCHED_RR</b> policies.<br><br><b>-v, --version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display version information and exit.<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a help message and exit.<br><br>


title: DESCRIPTION
content:
<b>chrt</b> is a command-line utility used to examine and change the real-time scheduling attributes of a process or a command. In Linux, real-time scheduling policies (<b>SCHED_FIFO</b> and <b>SCHED_RR</b>) are distinct from the default time-sharing policy (<b>SCHED_OTHER</b>). They are crucial for applications requiring predictable and low-latency execution, such as audio processing, robotics, or industrial control systems, where timely responses are critical.<br><br><b>SCHED_FIFO</b> (First-In, First-Out) ensures that a process runs until it voluntarily yields the CPU, blocks, or is preempted by a higher-priority <b>SCHED_FIFO</b> or <b>SCHED_RR</b> process. It does not allow time slicing. <b>SCHED_RR</b> (Round-Robin) is similar to <b>SCHED_FIFO</b> but includes a time quantum; if a process of the same priority is ready to run and its quantum expires, it will yield the CPU and be moved to the end of the run queue.<br><br><b>chrt</b> allows users to query the current policy and priority of an existing process by its PID or to launch a new command with specific real-time scheduling parameters. Real-time priorities typically range from 1 (lowest real-time) to 99 (highest real-time), with higher numbers indicating greater priority. This is separate from <i>nice</i> values, which affect the <b>SCHED_OTHER</b> policy.


title: CAVEATS
content:
Modifying real-time scheduling attributes typically requires elevated privileges (e.g., root access or the <b>CAP_SYS_NICE</b> capability) to prevent system instability. Misuse of real-time scheduling can lead to processes monopolizing the CPU, potentially causing system unresponsiveness or starvation of critical services if not managed carefully.


title: REAL-TIME PRIORITY RANGE
content:
For <b>SCHED_FIFO</b> and <b>SCHED_RR</b> policies, real-time priorities typically range from 1 to 99, where 99 is the highest priority. Lower values indicate lower real-time priority. You can query the maximum supported real-time priority using the <b>-m</b> option.


title: DEFAULT POLICY WHEN RUNNING A COMMAND
content:
When launching a new command without explicitly specifying a policy flag (e.g., <b>-f</b> or <b>-r</b>): if a <i>priority</i> is provided, <b>chrt</b> defaults to <b>SCHED_RR</b>. If no priority is given, the command runs with the default <b>SCHED_OTHER</b> policy.


title: HISTORY
content:
<b>chrt</b> is part of the <b>util-linux</b> package, a collection of essential system utilities for Linux. Its development is closely tied to the evolution of real-time capabilities within the Linux kernel, providing a user-space interface to the kernel's real-time scheduling policies. The demand for such a tool arose with the increasing use of Linux in time-critical applications, where precise control over process execution is paramount. It serves as a fundamental utility for configuring applications for predictable behavior on Linux systems.


title: SYNOPSIS
content:
<b>chsh</b> [<i>options</i>] [<i>username</i>]<br><b>chsh</b> <b>-l</b><br><b>chsh</b> <b>-s</b> <i>SHELL</i> [<i>username</i>]


title: PARAMETERS
content:
<b><b>-s</b>, <b>--shell</b> <i>SHELL</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the absolute path to the new login shell. The <i>SHELL</i> must be an executable and typically must be listed in the <I>/etc/shells</I> file for security validation.<br><br><b><b>-l</b>, <b>--list-shells</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists all available login shells that are currently permitted on the system. These shells are read from the <I>/etc/shells</I> file.<br><br><b><b>-u</b>, <b>--user</b> <i>USER</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Used exclusively by the root user to specify the login name of the user whose shell is to be changed. Regular users cannot use this option.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a brief help message explaining the command's usage and exits.<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information for the command and exits.<br><br>


title: DESCRIPTION
content:
The <b>chsh</b> command, short for "change shell," allows a user to change their login shell. The login shell is the program that runs immediately after a user logs into a system and interprets commands. <br><br>When executed by a regular user, <b>chsh</b> prompts for the user's current password to ensure authenticity and prevent unauthorized changes. Upon successful authentication, the user is prompted to enter the absolute path to the new desired shell.<br><br>For security reasons, <b>chsh</b> typically only permits users to specify shells that are explicitly listed in the <I>/etc/shells</I> file. This measure prevents users from setting arbitrary or potentially malicious programs as their login shell. If the specified shell is not in <I>/etc/shells</I>, the command will usually refuse the change.<br><br>The root user, however, possesses the privilege to change the login shell for any user on the system without requiring that user's password. Changes made by <b>chsh</b> take effect the next time the user logs in to the system.


title: CAVEATS
content:
The shell specified with <b>chsh</b> must be an existing executable on the system and, for security, typically must be present in the <I>/etc/shells</I> file. Setting an invalid, non-existent, or unlisted shell can lead to a user being unable to log in. For regular users, a password prompt ensures proper authentication before a shell change is permitted. Changes made by <b>chsh</b> do not take effect immediately but only upon the next successful login.


title: <I>/ETC/SHELLS</I> FILE
content:
This plain text file is central to the security and operation of <b>chsh</b>. It contains a list of all valid login shells that are allowed on the system, with each shell's absolute path on a new line (e.g., <I>/bin/bash</I>, <I>/usr/bin/zsh</I>). When a user attempts to change their shell, <b>chsh</b> consults this file to ensure the requested shell is sanctioned. This mechanism prevents users from assigning arbitrary programs (which could be insecure or malicious) as their default shell, thus bolstering system security.


title: PAM (PLUGGABLE AUTHENTICATION MODULES) INTEGRATION
content:
On modern Linux systems, <b>chsh</b> leverages PAM for its authentication process. PAM provides a modular framework that allows system administrators to configure various authentication methods (such as local passwords, LDAP, Kerberos, or multi-factor authentication) without altering the command's source code. The specific authentication policy for <b>chsh</b> is defined in its PAM configuration file, typically located at <I>/etc/pam.d/chsh</I>, which dictates how a user's identity is verified before a shell change is permitted.


title: HISTORY
content:
<b>chsh</b> is a fundamental utility present on virtually all Unix-like operating systems, reflecting its importance in user account management. On many Linux distributions, it is part of the <I>shadow-utils</I> package, which provides a suite of tools for secure user and group account administration. Its core functionality of modifying the user's shell entry in the system's password database (e.g., <I>/etc/passwd</I> or via NSS/PAM) has remained consistent for decades, serving as a standard method for users to customize their login environment.


title: PARAMETERS
content:
<b>NUMBER</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The virtual terminal number (typically 1-63) to switch to. This must be an existing and valid VT number.<br><br>


title: DESCRIPTION
content:
<b>chvt</b> is a simple command-line utility used to change the foreground virtual terminal (VT) on a Linux system. Virtual terminals are separate console sessions that can be accessed simultaneously. Typically, Linux systems provide several VTs (e.g., <i>tty1</i> through <i>tty6</i> for text consoles, and often <i>tty7</i> for the graphical environment like Xorg).<br><br><b>chvt</b> allows a user with appropriate permissions to switch the active VT from one to another by specifying the VT number. This is useful for quickly moving between different console-based tasks or checking logs on a separate console without disrupting a running graphical session (though Xorg can interfere). It operates by sending a <i>VT_ACTIVATE</i> ioctl to the console device.


title: CAVEATS
content:
<b>chvt</b> has a few important considerations:<br>1. Requires root privileges or <i>sudo</i> to execute, as changing the active virtual terminal is a system-wide operation.<br>2. Primarily effective on text-based consoles. When a graphical environment (like Xorg) is active, it often takes control of VT switching (e.g., using <i>Ctrl+Alt+Fx</i>), potentially blocking or altering <b>chvt</b>'s behavior.<br>3. Does not create a new virtual terminal; it only switches to an already existing one. If the target VT is inactive, it will present a login prompt.


title: PERMISSIONS
content:
For security and system stability, <b>chvt</b> requires elevated privileges, typically root access or execution via <i>sudo</i>. This is because switching virtual terminals is a global system action that could disrupt other users or processes, necessitating administrative control.


title: INTERACTION WITH XORG
content:
When a graphical desktop environment (like Xorg) is running, it usually occupies a specific virtual terminal (e.g., <i>tty7</i> on many systems). Xorg often intercepts and manages VT switching. While <b>chvt</b> can still be used to switch to a text console (e.g., <i>tty1</i>), returning to the active Xorg session might require specific graphical environment shortcuts (e.g., <i>Ctrl+Alt+F7</i>) rather than <b>chvt</b> itself.


title: HISTORY
content:
<b>chvt</b> is a long-standing utility within the <i>kbd</i> (keyboard utilities) package. Its functionality is intrinsically linked to the Linux kernel's virtual terminal subsystem, a foundational component of the Linux console since the operating system's early development. The command itself has remained remarkably stable, with its core function unchanged over the years, reflecting the mature and robust design of the VT subsystem.


title: SYNOPSIS
content:
<b>ci</b> [<i>options</i>] <i>file</i> ...<br><b>ci</b> [<i>options</i>] <b>-L</b>|<b>-U</b> [<i>file</i>] ...<br><b>ci</b> [<i>options</i>] <b>-r</b><i>[rev]</i> <b>-l</b>|<b>-u</b> [<i>file</i>] ...


title: PARAMETERS
content:
<b><b>-r</b><i>[rev]</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Specifies the revision number</b> to check in. If omitted, <b>ci</b> determines the next revision number. For example, <b>-r1.2</b> checks in revision 1.2.<br><br><b><b>-l</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Locks the new revision</b> after checking it in. This keeps the working file available for further editing and prevents others from checking in to the same branch.<br><br><b><b>-u</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Unlocks the new revision</b> after checking it in. This leaves the working file available but unlocked, allowing others to check in.<br><br><b><b>-m</b><i>message</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Uses the provided message string</b> as the log message for the new revision, bypassing the interactive editor.<br><br><b><b>-t</b><i>file</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Reads the log message</b> for the new revision from the specified <i>file</i>.<br><br><b><b>-q</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Operates quietly</b>, suppressing diagnostic output.<br><br><b><b>-f</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Forces the check-in</b> even if no changes were detected or if the file was not checked out using <b>co</b>.<br><br><b><b>-N</b><i>name</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Assigns a symbolic name (tag)</b> to the new revision. For example, <b>-Nstable_release</b>.<br><br><b><b>-s</b><i>state</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Sets the state attribute</b> of the new revision. Common states include <b>Exp</b> (experimental), <b>Rel</b> (release), <b>Stab</b> (stable).<br><br><b><b>-k</b><i>subst</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Sets the default keyword substitution mode</b> for future revisions checked out from this file.<br><br><b><b>-L</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Sets the default locking style</b> to 'strict', meaning <b>co</b> requires a lock before editing.<br><br><b><b>-U</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Sets the default locking style</b> to 'non-strict', meaning <b>co</b> does not require a lock before editing.<br><br><b><b>-w</b><i>[username]</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Sets the author's login name</b> for the new revision. If <i>username</i> is omitted, the current user's login name is used.<br><br><b><b>-d</b><i>[date]</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Uses the specified date and time</b> for the new revision. If omitted, the current time is used.<br><br><b><b>-z</b><i>[zone]</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<b>Specifies the time zone</b> for the new revision. If omitted, the current time zone is used.<br><br>


title: DESCRIPTION
content:
<b>ci</b> is the command used to check in changes from a working file into an RCS (Revision Control System) file. It creates a new revision of the file, storing the changes and associating them with a log message. When <b>ci</b> is invoked, it typically reads the working file, computes the differences from the previous revision, and stores these differences efficiently. It also records information such as the author, date, and a user-provided log message describing the changes made. After a successful check-in, <b>ci</b> usually removes the working file by default, leaving only the RCS file. This behavior can be altered using options like <b>-l</b> to keep the file locked for further editing or <b>-u</b> to keep it unlocked. <b>ci</b> is a fundamental part of the RCS workflow, enabling version control for individual files by managing their revision history within a special RCS directory.


title: CAVEATS
content:
RCS is designed for managing individual files, not entire projects with complex dependencies or directory structures. It lacks atomic commits across multiple files. Permissions on RCS files (e.g., <i>file</i>,v) are critical for proper operation. <b>ci</b> might prompt for a log message if <b>-m</b> or <b>-t</b> is not used, requiring an interactive session. Binary files often don't fare well with RCS's delta storage, though <b>-kb</b> can help for keyword substitution.


title: ENVIRONMENT VARIABLES
content:
The <b>EDITOR</b> environment variable is used to determine which text editor <b>ci</b> invokes for the log message if <b>-m</b> or <b>-t</b> options are not provided. If <b>EDITOR</b> is not set, <b>ci</b> typically defaults to <b>vi</b> or <b>ed</b>.


title: WORKING FILE HANDLING
content:
By default, <b>ci</b> removes the working file after a successful check-in. This behavior emphasizes that the RCS file (<i>file</i>,v) is the canonical source. Use <b>-l</b> or <b>-u</b> to retain the working file.


title: HISTORY
content:
RCS (Revision Control System) was originally developed by Walter F. Tichy at Purdue University in the early 1980s (first released around 1982-1985). <b>ci</b> is a core component, reflecting the system's focus on managing individual file revisions using a delta-storage mechanism. It was a prevalent version control system for Unix-like environments before more distributed and project-oriented systems like CVS, Subversion, and Git became popular. Despite its age, RCS is still found on many systems and remains useful for simple, single-file versioning tasks.


title: SYNOPSIS
content:
<B>cidr</B> <I>&lt;IP_ADDRESS/CIDR_BLOCK&gt;</I> [<I>OPTIONS</I>]<br>Example: <B>cidr</B> <I>192.168.1.0/24</I><br>Example: <B>cidr</B> <I>10.0.0.1/8 -v</I>


title: PARAMETERS
content:
<b><I>-h</I>, <I>--help</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help information about the command and exits.<br><br><b><I>-v</I>, <I>--verbose</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Provides more detailed output, potentially including binary representations of addresses or additional network statistics.<br><br><b><I>-n</I>, <I>--netmask</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs only the subnet mask (e.g., 255.255.255.0) for the given CIDR block.<br><br><b><I>-N</I>, <I>--network</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs only the network address (e.g., 192.168.1.0).<br><br><b><I>-B</I>, <I>--broadcast</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs only the broadcast address for the network.<br><br><b><I>-H</I>, <I>--hosts</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs the usable host IP address range (e.g., 192.168.1.1 - 192.168.1.254).<br><br><b><I>-c</I>, <I>--count</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs the total number of usable hosts within the specified CIDR block.<br><br>


title: DESCRIPTION
content:
The <B>cidr</B> command, as described here, is <B>not a standard, universally available utility</B> in most Linux distributions (e.g., Debian, Ubuntu, Fedora, CentOS). Instead, it represents a <B>conceptual tool</B> for performing <I>Classless Inter-Domain Routing</I> (CIDR) calculations. Its purpose is to take an IP address or a CIDR block as input and provide comprehensive details about the associated network. This typically includes the network address, broadcast address, subnet mask, the usable host IP range, and the total number of usable hosts within that specific subnet.<br><br>While a dedicated <B>cidr</B> command for general subnet arithmetic is not built-in, many network administrators and engineers develop custom scripts or utilize specialized third-party tools (like <B>ipcalc</B> or Python's <B>ipaddress</B> module) to achieve this functionality. Standard Linux commands like <B>ip</B> (from the <B>iproute2</B> suite) primarily focus on network interface configuration and routing, extensively using CIDR notation, but they do not provide the detailed subnet breakdown that a conceptual <B>cidr</B> tool would. This conceptual command aims to simplify the understanding and management of complex IP addressing schemes by dissecting CIDR blocks into their fundamental components.


title: CAVEATS
content:
The command <B>cidr</B> is <B>not a standard, universally available Linux command</B> included by default in most mainstream distributions. The analysis provided here describes a <B>conceptual network calculation tool</B> that performs operations commonly associated with CIDR blocks. Users typically achieve similar results by:<br>1. Utilizing existing network configuration tools like <B>ip</B> (for setting interface addresses with CIDR).<br>2. Writing custom scripts in languages like Python (leveraging the <B>ipaddress</B> module), Perl, or Bash.<br>3. Installing third-party utilities specifically designed for network calculations (e.g., <B>ipcalc</B>, <B>net-tools</B>).


title: CIDR NOTATION EXPLAINED
content:
CIDR notation combines an IP address with a suffix indicating the number of bits in the network prefix (e.g., 192.168.1.0<B>/24</B>). This prefix determines the network portion of the address, and the remaining bits define the host portion. For instance, a <B>/24</B> mask means the first 24 bits define the network, leaving 8 bits (256 addresses, including network and broadcast) for hosts. A <B>/16</B> would mean 16 bits for the network, leaving 16 bits for hosts, and so on.


title: PRACTICAL CIDR USAGE IN LINUX
content:
Even without a dedicated <B>cidr</B> command, Linux offers robust support for CIDR through its standard tools. For example, to assign an IP address using CIDR to an interface, you would use: <B>ip addr add</B> <I>192.168.1.10/24</I> <B>dev eth0</B>. To display the current configuration: <B>ip addr show eth0</B>. For more complex subnetting calculations or scripting, users often turn to programming languages like Python (with its built-in <B>ipaddress</B> module) or install utilities like <B>ipcalc</B> or <B>net-tools</B> (for `netmask` and `broadcast` calculations in some cases).


title: HISTORY
content:
The concept of <I>Classless Inter-Domain Routing</I> (CIDR) was introduced in 1993 by the IETF (RFCs 1518, 1519, 1520) to address the rapid exhaustion of IPv4 addresses and to improve routing efficiency on the Internet. It replaced the older Classful network addressing scheme by allowing for more flexible allocation of IP addresses through arbitrary-length prefixes. While a specific <B>cidr</B> command for general calculations did not become a standard part of Linux distributions, the <B>ip</B> command, developed as part of the <B>iproute2</B> suite (starting in the late 1990s) to supersede <B>ifconfig</B>, fully embraced and integrated CIDR notation into all its operations. The need for a dedicated 'CIDR calculator' utility often arises in network planning and troubleshooting, leading to the proliferation of many custom scripts and small open-source tools over the years to fill this niche.


title: SEE ALSO
content:
<B>ip</B>(8) (The primary Linux networking utility, which extensively uses CIDR notation for interface configuration, routing, and address management.), <B>netstat</B>(8) (Displays network connections, routing tables, and interface statistics, often showing IP addresses with CIDR masks.), <B>route</B>(8) (Manages IP routing table entries, where routes are frequently defined using CIDR notation.), <B>ifconfig</B>(8) (A legacy network configuration utility, which also utilized CIDR masks, largely superseded by <B>ip</B>.)


title: SYNOPSIS
content:
<b>cifs.idmap</b> [<i>options</i>] [<i>backend</i>]<br><b>cifs.idmap</b> <i>--id_to_sid</i> <I>type:id</I> [<i>options</i>] <i>backend</i><br><b>cifs.idmap</b> <i>--sid_to_id</i> <I>type:sid</I> [<i>options</i>] <i>backend</i>


title: PARAMETERS
content:
<b><b>-c</b>, <b>--create</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Create a new ID map entry. Typically used when running as a daemon or adding specific mappings.<br><br><b><b>-d</b>, <b>--delete</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Delete an existing ID map entry.<br><br><b><b>-D</b> <i>&lt;domain&gt;</i>, <b>--domain</b> <i>&lt;domain&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the domain name for the ID mapping operation. Essential for multi-domain setups.<br><br><b><b>-p</b> <i>&lt;path&gt;</i>, <b>--path</b> <i>&lt;path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Path to a file (e.g., TDB file) used by certain backends to store ID mappings.<br><br><b><b>-s</b> <i>&lt;server&gt;</i>, <b>--server</b> <i>&lt;server&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the CIFS server name for the mapping operation.<br><br><b><b>-u</b> <i>&lt;uid&gt;</i>, <b>--uid</b> <i>&lt;uid&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a Linux UID for conversion to a Windows SID.<br><br><b><b>-g</b> <i>&lt;gid&gt;</i>, <b>--gid</b> <i>&lt;gid&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a Linux GID for conversion to a Windows SID.<br><br><b><b>-w</b> <i>&lt;sid&gt;</i>, <b>--sid</b> <i>&lt;sid&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify a Windows SID for conversion to a Linux UID/GID.<br><br><b><b>--id_to_sid</b> <i>&lt;type:id&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Request conversion from a Linux ID (e.g., 'uid:1000' or 'gid:500') to a Windows SID.<br><br><b><b>--sid_to_id</b> <i>&lt;type:sid&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Request conversion from a Windows SID (e.g., 'S-1-5-21-...') to a Linux ID.<br><br><b><b>--backend</b> <i>&lt;backend&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specify the ID mapping backend to use (e.g., <i>sfu</i>, <i>rid</i>, <i>nss</i>, <i>tdb</i>). This is often a mandatory argument for direct operations.<br><br><b><b>-v</b>, <b>--verbose</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Increase verbosity of output for debugging purposes.<br><br><b><b>--debug</b> <i>&lt;level&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Set the debug level for more detailed diagnostic output.<br><br>


title: DESCRIPTION
content:
<i>cifs.idmap</i> is a crucial utility within the <b>cifs-utils</b> package designed to manage the translation of Windows Security Identifiers (SIDs) to Linux User IDs (UIDs) and Group IDs (GIDs), and vice-versa. This mapping is essential for ensuring correct file ownership, permissions, and Access Control Lists (ACLs) when Linux clients mount and interact with CIFS/SMB shares, particularly in environments leveraging Active Directory for user and group management.<br><br>It functions by interacting with the Linux kernel's CIFS module, providing the necessary identity translations. <i>cifs.idmap</i> supports various backends (e.g., <i>sfu</i>, <i>rid</i>, <i>nss</i>, <i>tdb</i>) to perform the actual mapping resolution, often relying on services like <i>sssd</i> or <i>winbind</i>. Its primary role is to bridge the identity gap between the Windows and Linux security models, allowing for seamless and consistent user/group identity management across heterogeneous file systems. While it can be invoked directly for specific lookups, it often runs as a daemon or is implicitly used by <i>mount.cifs</i> when ID mapping is enabled on a mount.


title: CAVEATS
content:
<ul><li>Requires the <b>cifs-utils</b> package to be installed on the Linux system.</li><li>Proper configuration of the chosen ID mapping backend (e.g., <i>sssd</i>, <i>winbind</i>, <i>smb.conf</i> for specific Samba configurations) is absolutely critical for <i>cifs.idmap</i> to function correctly.</li><li>Misconfiguration can lead to incorrect file ownership, permission issues, or inaccessible files on CIFS/SMB shares.</li><li>Kernel support for CIFS ID mapping must be present and enabled.</li><li>Interaction with Active Directory or other directory services requires correct network and DNS resolution.</li></ul>


title: ID MAPPING BACKENDS
content:
<i>cifs.idmap</i> supports several backends to resolve ID mappings:<br><ul><li><b>sfu</b>: Maps UIDs/GIDs to SIDs based on the 'Services for Unix' (SFU) attributes in Active Directory.</li><li><b>rid</b>: Maps Windows Relative IDs (RIDs) within a domain to Linux UIDs/GIDs, often used for mapping AD users/groups to a specific UID/GID range on Linux.</li><li><b>nss</b>: Leverages the Name Service Switch (NSS) framework (e.g., <i>nss_winbind</i> or <i>nss_sss</i>) to query the system's user/group database. This is a common and flexible approach.</li><li><b>tdb</b>: Uses a TDB (Trivial Database) file to store static, manually configured mappings. Less common for dynamic environments.</li><li><b>file</b>: Uses simple text files for static mappings.</li></ul>The choice of backend is crucial and depends on the specific environment and directory service configuration.


title: INTERACTION WITH MOUNT.CIFS AND KEYRINGS
content:
When a CIFS share is mounted with ID mapping enabled (e.g., using the <i>idmap</i> mount option), the Linux kernel's CIFS module makes requests to the <i>request-key</i> facility. <i>request-key</i> then invokes <i>cifs.idmap</i> (usually configured via <i>/etc/request-key.conf</i>) to perform the actual ID mapping. <i>cifs.idmap</i> communicates with the chosen backend (e.g., <i>sssd</i> or <i>winbind</i>) to get the translation and returns the result to the kernel, which then uses it to determine file ownership and permissions. This interaction is mostly transparent to the end-user once configured.


title: HISTORY
content:
<i>cifs.idmap</i> is part of the <b>cifs-utils</b> project, which provides a set of tools for managing CIFS/SMB mounts on Linux. Its development has been driven by the increasing need for robust and efficient identity management in mixed Linux/Windows environments, particularly with the widespread adoption of Active Directory. Earlier methods of ID mapping often relied solely on user-space daemons like <i>winbindd</i> or bespoke scripts. <i>cifs.idmap</i>, along with advancements in the kernel's CIFS module, enables more integrated and performant ID mapping, allowing the kernel to directly handle ID translation requests by consulting the configured backend, thus improving consistency and reducing overhead for large-scale deployments.


title: SYNOPSIS
content:
<b>cifs.upcall</b> [<i>--krb5</i>] [<i>--help</i>] [<i>--version</i>] <i>&lt;call_type&gt; &lt;arguments&gt;</i>


title: PARAMETERS
content:
<b><i>--krb5</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Used to signal that the upcall relates to Kerberos authentication. This flag is typically set when handling Kerberos ticket acquisition.<br><br><b><i>--help</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a brief usage message and exits.<br><br><b><i>--version</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the version number of the <b>cifs.upcall</b> utility and exits.<br><br><b><i>&lt;call_type&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the type of operation the kernel module needs assistance with. Common types include <b>key</b> (for managing authentication keys like NTLM or Kerberos tickets), <b>dfs</b> (for resolving Distributed File System referrals), <b>gid.krb5</b>, <b>uid.krb5</b>, <b>gid.idmap</b>, <b>uid.idmap</b>, <b>gid.sids</b>, <b>uid.sids</b> (for ID mapping), among others.<br><br><b><i>&lt;arguments&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Additional parameters specific to the <i>&lt;call_type&gt;</i>, providing context or data for the operation. For example, for <b>key</b> types, it might include the UID, mount ID, and server principal.<br><br>


title: DESCRIPTION
content:
<b>cifs.upcall</b> is a user-space helper program invoked by the Linux kernel's CIFS (Common Internet File System) module. Its primary role is to facilitate operations that require interaction with user-space services, which the kernel cannot perform directly. This typically includes authentication processes, particularly for NTLM and Kerberos, and resolving DFS (Distributed File System) referrals.<br><br>When the kernel needs a user-space service (e.g., obtaining a Kerberos ticket, hashing a password for NTLMv2, or handling a DFS redirect), it makes an "upcall" to <b>cifs.upcall</b>. This utility then interacts with system components like <i>keyutils</i> for managing authentication credentials (like NTLM hashes or Kerberos tickets) or Kerberos client tools (e.g., <i>kinit</i>). It plays a crucial role in enabling secure and complex CIFS/SMB access from Linux systems, especially when dealing with Active Directory environments or highly structured network shares. It is not typically run directly by users but is invoked automatically by the kernel.


title: CAVEATS
content:
<i>cifs.upcall</i> is primarily a kernel helper and is not intended for direct interactive use by end-users. Its proper functioning relies heavily on correct configuration of the system's key management facilities (e.g., <i>keyutils</i>) and, for Kerberos, the Kerberos client setup (e.g., <i>krb5-user</i> package and <i>/etc/krb5.conf</i>). Issues often manifest as authentication failures or inability to access certain network resources, and troubleshooting usually involves examining kernel logs (<i>dmesg</i>) and system logs for related errors.


title: INTEGRATION WITH KEY MANAGEMENT
content:
<i>cifs.upcall</i> frequently interacts with the kernel's keyring service via the <i>keyutils</i> utilities. For NTLM authentication, it can store and retrieve NTLM hashes. For Kerberos, it manages Kerberos tickets by interacting with the Kerberos client libraries (e.g., via <i>kinit</i> if necessary) and then storing the resulting tickets in the kernel keyring, making them available for subsequent CIFS operations.


title: KERNEL INVOCATION
content:
Unlike most commands, <i>cifs.upcall</i> is typically not executed manually by a user. Instead, it is automatically spawned by the Linux kernel's CIFS module (<i>cifs.ko</i>) when it encounters a situation that requires user-space assistance, such as during a mount operation involving Kerberos authentication or when resolving a DFS path.


title: HISTORY
content:
The Linux CIFS client implementation has evolved significantly over the years to support modern SMB protocols and features. As the kernel's CIFS module gained capabilities such as Kerberos authentication and Distributed File System (DFS) support, the need for a user-space helper became apparent. <i>cifs.upcall</i> was developed as part of the <i>cifs-utils</i> package to bridge this gap, allowing the kernel to offload complex user-space interactions, particularly for secure authentication methods and DFS resolution, to a dedicated utility. Its development reflects the increasing sophistication of Linux's integration with Windows-based network services.


title: SYNOPSIS
content:
<i>cifscreds</i> <b>add</b> &lt;host&gt; &lt;user&gt; [<b>-p</b> &lt;password&gt;] [<b>-d</b> &lt;domain&gt;]<br><i>cifscreds</i> <b>update</b> &lt;host&gt; &lt;user&gt; [<b>-p</b> &lt;password&gt;] [<b>-d</b> &lt;domain&gt;]<br><i>cifscreds</i> <b>clear</b> &lt;host&gt; &lt;user&gt;<br><i>cifscreds</i> <b>list</b><br><i>cifscreds</i> <b>delete</b> &lt;host&gt; &lt;user&gt;


title: PARAMETERS
content:
<b><b>add</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Adds a new CIFS credential to the kernel keyring.<br><br><b><b>update</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Updates an existing CIFS credential for the specified host and user.<br><br><b><b>clear</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Clears the password associated with a specific host and user in the keyring. The entry remains but without a password.<br><br><b><b>list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists all CIFS credentials currently stored in the keyring, including host, user, and password (if available).<br><br><b><b>delete</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Deletes a specific CIFS credential entry entirely from the keyring.<br><br><b>&lt;host&gt;</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The target CIFS server hostname or IP address.<br><br><b>&lt;user&gt;</b><br>&nbsp;&nbsp;&nbsp;&nbsp;The username for authentication on the CIFS server.<br><br><b><b>-p</b> &lt;password&gt;</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the password for the given user. If omitted, the command will prompt securely for the password.<br><br><b><b>-d</b> &lt;domain&gt;</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the domain name for the user's account.<br><br>


title: DESCRIPTION
content:
<i>cifscreds</i> is a utility designed to manage CIFS/SMB authentication credentials within the Linux kernel's keyring service. It allows users to store, retrieve, update, and clear usernames, passwords, and domains associated with specific CIFS hosts.<br><br>By leveraging the kernel keyring, <i>cifscreds</i> offers a more secure method for handling sensitive login information compared to traditional plain-text credential files or passing passwords directly on the command line. This stored information can then be securely accessed by CIFS client utilities like <i>mount.cifs(8)</i> through specific options, such as <b>creds=&lt;key_id&gt;</b> or <b>credentials=&lt;key_id&gt;</b>. This prevents sensitive data from being exposed in process listings or command history, enhancing system security for network file system mounts. It specifically manages keys of type "cifs" in the user's or session keyring.


title: CAVEATS
content:
While <i>cifscreds</i> enhances security by using the kernel keyring, listing credentials with <i>cifscreds</i> <b>list</b> will display passwords in plain text on the terminal. Users should be aware of terminal logging and shoulder-surfing risks. Credentials stored are typically tied to the user's session or specific user keyring, meaning they might not persist across reboots unless managed by a system-wide keyring service.


title: KEYRING INTEGRATION WITH <I>MOUNT.CIFS</I>
content:
To utilize credentials stored by <i>cifscreds</i> with <i>mount.cifs</i>, you can specify the <b>creds</b> or <b>credentials</b> mount option with the key ID of the stored credential. For example, <b>mount -t cifs //server/share /mnt/point -o credentials=&lt;key_id&gt;</b>. The key ID can be obtained from the <i>cifscreds</i> <b>list</b> output.


title: PASSWORD PROMPT
content:
If the <b>-p</b> or <b>--password</b> option is not provided when adding or updating credentials, <i>cifscreds</i> will securely prompt the user for the password, preventing it from appearing in command history or process lists.


title: HISTORY
content:
The <i>cifscreds</i> utility is part of the <b>cifs-utils</b> package, which provides various tools for interacting with CIFS/SMB network shares on Linux. It was introduced to address the need for a more secure and convenient way to manage authentication credentials for <i>mount.cifs</i> operations, moving away from less secure methods like storing passwords directly in <b>fstab</b> or on the command line. Its development reflects the ongoing effort to improve security and usability of network file system clients in Linux.


title: PARAMETERS
content:
<b>-d</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display the device utilization report. This is the default behavior if no unit option is specified.<br><br><b>-k</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display statistics in kilobytes (KB) per second. This changes the unit of reported throughput from bytes to kilobytes.<br><br><b>-m</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display statistics in megabytes (MB) per second. This changes the unit of reported throughput from bytes to megabytes.<br><br><b>-h</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a brief help message explaining the command's usage and options, then exit.<br><br><b>-V</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display the version number of the <i>cifsiostat</i> command (and the <i>sysstat</i> package it belongs to), then exit.<br><br><b>INTERVAL</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the time in seconds between each report. If omitted, a single report containing statistics since system boot is displayed.<br><br><b>COUNT</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the number of reports to be generated. This parameter is only valid if <i>INTERVAL</i> is also specified.<br><br>


title: DESCRIPTION
content:
<i>cifsiostat</i> is a command-line utility used for reporting CIFS (Common Internet File System), also known as SMB (Server Message Block), I/O statistics. It is part of the <i>sysstat</i> package, which provides various system performance monitoring tools for Linux.<br><br>Unlike <i>iostat</i>, which reports general block device I/O statistics, <i>cifsiostat</i> specifically focuses on I/O operations related to mounted CIFS network shares. It provides metrics such as read/write operations per second, read/write bytes per second, and read/write request sizes for each active CIFS mount point.<br><br>This command is invaluable for system administrators and network engineers who need to diagnose performance bottlenecks or monitor the usage of network file shares accessed via the CIFS protocol. By observing the I/O patterns, users can identify if a particular CIFS share is experiencing high load or if network performance is impacting file operations.


title: CAVEATS
content:
<i>cifsiostat</i> relies on the kernel's ability to expose CIFS statistics, typically found in <i>/proc/fs/cifs/Stats</i> or similar kernel interfaces. Its functionality is dependent on the CIFS module being loaded and actively used for mounted shares. If no CIFS shares are mounted or the kernel does not expose the necessary statistics, the command may report no data or an error. It provides statistics only for CIFS mounts, not for other network file systems like NFS, or local disk I/O.


title: DATA SOURCE
content:
<i>cifsiostat</i> gathers its data directly from the Linux kernel's CIFS module statistics. These statistics include information on read/write operations, bytes transferred, and average request sizes, providing a granular view of I/O performance on CIFS mounted shares.


title: UNITS OF MEASUREMENT
content:
By default, <i>cifsiostat</i> reports throughput in bytes per second. Users can easily switch to more readable units like kilobytes per second (<b>-k</b>) or megabytes per second (<b>-m</b>) for easier interpretation of high-volume data transfers.


title: HISTORY
content:
<i>cifsiostat</i> is part of the long-standing <i>sysstat</i> project, a comprehensive collection of performance monitoring tools for Linux. The <i>sysstat</i> package (which includes tools like <i>iostat</i>, <i>sar</i>, <i>mpstat</i>, etc.) has been continuously developed since the early 2000s, providing essential insights into system resource utilization. <i>cifsiostat</i> was specifically added to address the growing need for dedicated monitoring of CIFS/SMB network file system performance, reflecting the widespread adoption of Windows-compatible file sharing in Linux environments.


title: SYNOPSIS
content:
The command line executable most commonly associated with initiating or managing a <i>Cinnamon</i> session is typically:<br><B>cinnamon-session</B> [<i>OPTIONS</i>]<br><br>While <B>cinnamon</B> refers to the desktop environment itself, it is usually launched automatically by a display manager (e.g., LightDM, GDM) upon user login, rather than directly invoked by a user from the terminal.


title: PARAMETERS
content:
<b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help options for the <i>cinnamon-session</i> executable.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the version information of the <i>cinnamon-session</i> executable.<br><br><b>--session=SESSION</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts the session using a specific session definition file.<br><br><b>--builtin</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts a builtin session, typically used for default configurations.<br><br><b>--debug</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables debug output for troubleshooting session startup issues.<br><br><b>--failsafe</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Starts the session in a failsafe mode, often with default settings and no custom configurations, useful for recovery.<br><br>


title: DESCRIPTION
content:
<i>Cinnamon</i> is a free and open-source desktop environment for GNU/Linux and other Unix-like operating systems. Primarily developed by the <B>Linux Mint</B> community, it is a prominent fork of <B>GNOME 3</B>.<br><br>Designed to offer a traditional user experience, <i>Cinnamon</i> integrates modern aesthetics with a familiar desktop metaphor, featuring a bottom panel, an applications menu, desktop icons, and window lists. Its goal is to provide a user-friendly, powerful, and highly customizable interface that appeals to users who prefer a classic desktop layout while incorporating contemporary technologies and features.<br><br>Key components of <i>Cinnamon</i> include the <B>Muffin</B> window manager (a fork of Mutter), the <B>Cinnamon Settings</B> application for system configuration, and a robust ecosystem for <B>applets</B>, <B>desklets</B>, and <B>extensions</B>, enabling extensive personalization. The design philosophy emphasizes stability, comfort, and ease of use, making it a popular choice, particularly for Linux Mint users.


title: CAVEATS
content:
The term <B>cinnamon</B> primarily refers to the desktop environment itself, not a typical command-line utility run directly by users for specific tasks.<br><br>Attempting to run <B>cinnamon</B> or <B>cinnamon-session</B> directly from a terminal within an already running <i>Cinnamon</i> graphical session can lead to unexpected behavior, errors, or conflicts, as it tries to start a new instance of the desktop environment.<br><br>Its primary method of invocation is via a display manager during the login process, and its management usually involves system-level configurations rather than direct command-line interaction.


title: CORE PURPOSE
content:
<i>Cinnamon</i> is not a standalone command-line utility for specific tasks, but rather the complete graphical desktop environment itself. Its existence defines the user's interactive graphical experience on a system where it is installed.


title: MODULARITY AND CUSTOMIZATION
content:
The desktop environment is highly modular. Users can extend its functionality and appearance through:<br><B>Applets</B>: Small applications displayed on the panel (e.g., weather, system monitors).<br><B>Desklets</B>: Widgets displayed directly on the desktop (e.g., sticky notes, picture frames).<br><B>Extensions</B>: Alter or add functionality to <i>Cinnamon</i>'s core behavior or user interface.


title: HISTORY
content:
<i>Cinnamon</i> was conceived and developed by the <B>Linux Mint</B> team as a distinct desktop environment following the release of <B>GNOME 3</B> and its <B>GNOME Shell</B> interface. Many users found <B>GNOME Shell</B> to be a significant departure from the traditional desktop metaphor.<br><br>First publicly released in 2011, <i>Cinnamon</i> aimed to provide a user experience that maintained the familiar desktop paradigm (panels, menus, desktop icons) while leveraging the underlying modern technologies of <B>GNOME 3</B>. It quickly became the flagship desktop environment for <B>Linux Mint</B>, playing a crucial role in its popularity by offering a comfortable and intuitive environment to users migrating from older operating systems or other Linux desktops.


title: SEE ALSO
content:
gnome-session(1), startx(1), lightdm(1), gdm(1), cinnamon-settings(1), cinnamon-screensaver-command(1)


title: PARAMETERS
content:
<b>TYPE</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the type of Cinnamon component to manage. Possible values are: <b>applet</b>, <b>desklet</b>, <b>extension</b>, or <b>theme</b>.<br><br><b>COMMAND</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the action to perform on the chosen component type. Possible values are: <b>install</b>, <b>remove</b>, <b>enable</b>, <b>disable</b>, or <b>list</b>.<br><br><b>ARGUMENT</b><br>&nbsp;&nbsp;&nbsp;&nbsp;This parameter is context-dependent based on the chosen <i>COMMAND</i>. <br><ul><li>For <b>install</b>: It expects the <i>PATH_TO_ZIP</i> file of the component (e.g., <i>/home/user/my_extension.zip</i>).</li><li>For <b>remove</b>, <b>enable</b>, or <b>disable</b>: It expects the <i>UUID</i> (Unique User ID) of the installed component (e.g., <i>example@extension.org</i>).</li><li>For <b>list</b>: No argument is required.</li></ul><br><br>


title: DESCRIPTION
content:
The <b>cinnamon-extension-tool</b> is a command-line utility designed for the Cinnamon desktop environment. It provides a convenient way for users and developers to interact with various Cinnamon components, including extensions, applets, desklets, and themes. This tool simplifies tasks such as installing new components from .zip files, removing existing ones, enabling or disabling installed items, and listing all available components of a specific type. It's particularly useful for scripting automation, troubleshooting, or for users who prefer command-line interaction over graphical interfaces for managing their Cinnamon environment. The tool ensures proper handling of component files and configurations within the Cinnamon ecosystem, providing a robust interface for system management.


title: CAVEATS
content:
This command is specific to the Cinnamon desktop environment. <br>Changes made, especially enabling or disabling components, may require restarting Cinnamon (e.g., by logging out and back in, or pressing <i>Alt+F2</i> and typing <i>r</i>) for the changes to take full effect. <br>Component files are typically installed into <i>~/.local/share/cinnamon/{applets,desklets,extensions,themes}</i>.


title: USAGE EXAMPLES
content:
Here are some common examples of how to use the <b>cinnamon-extension-tool</b>:<br><br><b>List all installed extensions:</b><br><i>cinnamon-extension-tool extension list</i><br><br><b>Install a new desklet from a local zip file:</b><br><i>cinnamon-extension-tool desklet install /path/to/my_custom_desklet.zip</i><br><br><b>Enable a specific applet by its UUID:</b><br><i>cinnamon-extension-tool applet enable 'my_applet_uuid@example.com'</i><br><br><b>Remove a theme:</b><br><i>cinnamon-extension-tool theme remove 'MyThemeName'</i>


title: HISTORY
content:
The <b>cinnamon-extension-tool</b> was developed as an integral part of the Cinnamon desktop environment, which originated as a fork of GNOME Shell in 2011. Its creation aimed to provide a dedicated command-line interface for managing Cinnamon's unique components (applets, desklets, extensions, and themes), offering an alternative to graphical management tools. Over time, it has evolved alongside the Cinnamon desktop, maintaining compatibility and expanding its functionality to support the growing ecosystem of Cinnamon components, proving invaluable for both developers and users preferring command-line workflows.


title: PARAMETERS
content:
<b><i>APPLICATION_ID</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The registered application ID, usually derived from a <i>.desktop</i> file's <b>Name</b> or <b>StartupWMClass</b>, for launching a known application.<br><br><b><i>PATH_TO_DESKTOP_FILE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The full path to a <i>.desktop</i> file (e.g., <i>/usr/share/applications/firefox.desktop</i>) to be executed directly.<br><br><b><i>URI</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;A Uniform Resource Identifier (e.g., <i>http://example.com</i>, <i>file:///path/to/document.pdf</i>) to be opened by its default handler within the Cinnamon context.<br><br>


title: DESCRIPTION
content:
<b>cinnamon-launcher</b> is an internal utility primarily used within the Cinnamon desktop environment to facilitate the launching of applications, documents, or URIs. It typically processes <i>.desktop</i> files, which are standard entries describing how to launch a specific application, its icon, categories, and other metadata.<br><br>While not commonly invoked directly by users from the command line, it plays a crucial role in how the Cinnamon desktop environment opens applications when clicked from the menu, panel, or file manager. It handles various aspects such as environment variables, working directories, and ensuring the application is launched correctly in the graphical session. It may also interact with <b>xdg-open</b> or similar mechanisms for handling URI schemes, providing a consistent launch experience for the user.


title: CAVEATS
content:
<b>cinnamon-launcher</b> is primarily an internal component of the Cinnamon desktop environment. Users typically do not invoke it directly from the command line, and it has few, if any, command-line options for direct user control. Its behavior is heavily dependent on the content of the <i>.desktop</i> files it processes. This command is specific to Cinnamon and may not exist or behave identically on other desktop environments (like GNOME, KDE, or XFCE).


title: .DESKTOP FILES
content:
<i>.desktop</i> files are crucial for <b>cinnamon-launcher</b>'s operation. These plain text files conform to the XDG Desktop Entry Specification and contain metadata about applications, such as their name, icon, categories, and the <b>Exec</b> key which specifies the command to run. <b>cinnamon-launcher</b> parses these files to correctly launch the intended application with its associated properties.


title: INTEGRATION WITH CINNAMON SHELL
content:
<b>cinnamon-launcher</b> is deeply integrated with the Cinnamon Shell, handling requests from the menu, panel launchers, file manager (Nemo), and other Cinnamon components. It provides a consistent interface for the desktop to start processes, manage their environment, and potentially track their lifecycle (e.g., for showing "application is starting" indicators).


title: HISTORY
content:
The <b>cinnamon-launcher</b> command is an integral part of the Cinnamon desktop environment, which originated as a fork of GNOME Shell in 2011 by Linux Mint developers. As such, its development is closely tied to the evolution of Cinnamon itself. It likely emerged as a dedicated component to manage application launching, leveraging existing XDG (freedesktop.org) specifications for <i>.desktop</i> files, ensuring compatibility and consistent behavior across different desktop environments adhering to these standards. Its focus has always been on providing a robust and seamless user experience within Cinnamon for opening applications and files.


title: PARAMETERS
content:
<b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message with command-line options.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the version information of the menu editor.<br><br><b><b>--display</b>=<I>DISPLAY</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the X display to use for the graphical application.<br><br>


title: DESCRIPTION
content:
<b>cinnamon-menu-editor</b> is the official graphical tool for managing the Cinnamon desktop environment's application menu. It provides a user-friendly interface to customize application launchers, categories, and their properties. Users can easily add new applications, modify existing ones (changing their name, command, icon, or category), or remove unwanted entries. It also allows reorganizing the menu by creating new submenus or moving applications between categories. The editor directly interacts with standard <I>.desktop</I> files located in the user's home directory (primarily <I>~/.local/share/applications/</I>) and configuration files in <I>~/.config/menus/</I>, ensuring compliance with the FreeDesktop.org Desktop Entry Specification. This tool is essential for personalizing the Cinnamon desktop experience, allowing users to tailor their menu to their specific needs and workflow.


title: CAVEATS
content:
As a graphical application, <b>cinnamon-menu-editor</b> is not designed for command-line scripting or batch operations. It requires a running Cinnamon desktop environment and X server to function correctly. Modifications made via this editor primarily affect the current user's menu and do not alter system-wide application installations. Incorrectly editing or deleting crucial menu entries can potentially lead to missing or broken application launchers in your menu.


title: CONFIGURATION FILES
content:
This editor primarily manages application launchers by creating or modifying <I>.desktop</I> files in your user's local applications directory (typically <I>~/.local/share/applications/</I>). It also manages menu categories and structure through XML configuration files located in <I>~/.config/menus/</I>.


title: HISTORY
content:
<b>cinnamon-menu-editor</b> is an integral component of the <I>Cinnamon</I> desktop environment, which originated as a fork of GNOME 3. It was developed to provide a familiar and robust menu editing experience, reminiscent of earlier GNOME versions (like <I>alacarte</I>, the GNOME 2 menu editor). Its primary goal is to empower users with simple, visual control over their application launchers and menu structure, adhering to FreeDesktop.org standards for <I>.desktop</I> files. Its development parallels the evolution of Cinnamon itself, focusing on stability and user-friendliness.


title: SYNOPSIS
content:
<b>cinnamon-screensaver</b> [<i>OPTIONS</i>]<br><b>cinnamon-screensaver</b> <b>--lock</b><br><b>cinnamon-screensaver</b> <b>--activate</b>


title: PARAMETERS
content:
<b><b>--lock</b>, <b>--activate</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Immediately locks the screen and activates the screensaver. This is the most common way to manually lock the session.</i><br><br><b><b>--no-daemon</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Runs the screensaver process in the foreground, preventing it from detaching as a daemon. This option is primarily useful for debugging or testing purposes.</i><br><br><b><b>--debug</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Enables verbose debugging output to the console. This provides detailed information about the screensaver's operations, aiding in troubleshooting.</i><br><br><b><b>--status</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Queries and prints the current status of the screensaver (e.g., 'active' or 'inactive').</i><br><br><b><b>--disable</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Disables the screensaver, preventing it from activating automatically or manually until re-enabled.</i><br><br><b><b>--enable</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Enables the screensaver, allowing it to function normally according to its configuration.</i><br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<i>Displays the version information of the <b>cinnamon-screensaver</b> utility and then exits.</i><br><br>


title: DESCRIPTION
content:
The <b>cinnamon-screensaver</b> command is the official screen locking and screensaver component for the <I>Cinnamon desktop environment</I>.<br><br>Its primary function is to <i>secure user sessions</i> when they step away from their computer. It can be configured to automatically activate after a period of inactivity or can be manually triggered. When active, it displays a chosen screensaver or a blank screen, effectively preventing unauthorized access.<br><br>To regain control of the session, the user must provide their password, ensuring the integrity and privacy of the system. It plays a crucial role in the overall security posture of a Cinnamon-based system, integrating seamlessly with the desktop's power management and session management features. This utility ensures that sensitive information displayed on the screen is protected from prying eyes when the user is not present.


title: CAVEATS
content:
<i>If not properly configured (e.g., no password set for the user, or an easily guessable password), the screen locker provides minimal security.</i><br><br><i>In some rare cases, specific graphics driver issues or compositor conflicts can lead to display problems (e.g., blank screens or inability to unlock) when the screensaver activates.</i><br><br><i>Authentication for unlocking relies on <I>PAM (Pluggable Authentication Modules)</I>; therefore, any misconfiguration in PAM can directly affect the ability to unlock the screen.</i>


title: INTEGRATION WITH POWER MANAGEMENT
content:
<i><b>cinnamon-screensaver</b> is deeply integrated with Cinnamon's power management settings. It respects system power-saving configurations, often initiating screen locking or dimming after specific idle periods defined by the user in the system settings or via systemd.</i>


title: USER INTERFACE CONFIGURATION
content:
<i>While the command-line offers basic control for immediate actions or debugging, most users configure <b>cinnamon-screensaver</b>'s behavior (e.g., lock delay, screensaver theme, password requirement) via the Cinnamon System Settings GUI, typically accessible under the 'Screensaver' or 'Privacy' sections.</i>


title: HISTORY
content:
<b>cinnamon-screensaver</b> emerged as an integral part of the <I>Cinnamon desktop environment</I>, which itself was created as a fork of <I>GNOME 3</I> in response to design changes introduced in <I>GNOME Shell</I>. Consequently, <b>cinnamon-screensaver</b> inherited much of its foundational design and functionality from its predecessors, such as <I>gnome-screensaver</I> (or similar components from the <I>GNOME 2</I> era), adapting it to the specific needs and aesthetics of the <I>Cinnamon desktop</I>.<br><br>Its development has consistently focused on providing a stable, secure, and user-friendly screen locking experience that integrates seamlessly with Cinnamon's traditional desktop metaphor and system-wide services.


title: PARAMETERS
content:
<b>--session=<i>SESSION_NAME</i>, -s <i>SESSION_NAME</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies a particular session to load, allowing for different desktop configurations to be started.<br><br><b>--debug</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables debug output, providing verbose information about the session startup and management process, which is useful for troubleshooting.<br><br><b>--systemd-integration</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables or disables integration with systemd, affecting how processes are managed within the user's session.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the version of <b>cinnamon-session</b> and exits.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a summary of available command-line options.<br><br>


title: DESCRIPTION
content:
<b>cinnamon-session</b> is the core session manager responsible for starting, managing, and ending the Cinnamon desktop environment. It's typically the first program launched by the display manager (such as LightDM, GDM, or SDDM) after a user logs in, initiating the full graphical desktop experience. Its primary role involves executing all necessary applications and components that constitute the Cinnamon desktop, including the window manager (Muffin), the panel, the desktop background, applets, and various background services. <b>cinnamon-session</b> ensures that these components are started in the correct order, monitors their status, and handles the graceful termination of applications during logout, shutdown, or reboot sequences. By orchestrating the launch and lifecycle of the desktop environment's processes, it provides a cohesive and stable user experience. It integrates with XDG Autostart specifications to launch user-defined applications and services upon login.


title: CAVEATS
content:
Users generally should <i>not</i> launch <b>cinnamon-session</b> directly from the command line, as it is typically started by a display manager or <b>startx</b>. Manually launching it might lead to unexpected behavior or a broken session if an X server is not already running or other critical session components are not correctly managed.<br><br>Its proper functioning relies heavily on well-configured XDG Autostart <i>.desktop</i> files located in system-wide and user-specific autostart directories.<br><br>Problems with <b>cinnamon-session</b> can prevent the entire desktop environment from starting or cause unexpected shutdowns. The exact behavior and available options might vary slightly between different Cinnamon versions and Linux distributions.


title: XDG AUTOSTART INTEGRATION
content:
<b>cinnamon-session</b> extensively uses the XDG Autostart specification to automatically launch applications and services configured for the user's session. These configurations are typically found in <i>.desktop</i> files in system-wide directories (e.g., <i>/etc/xdg/autostart</i>) and user-specific directories (e.g., <i>~/.config/autostart</i>).


title: D-BUS COMMUNICATION
content:
It communicates with various desktop components and services primarily through D-Bus, an inter-process communication system. This enables dynamic management of the session, including handling power management events, application restarts, and session state changes.


title: SESSION MANAGEMENT PROTOCOL (XSMP)
content:
<b>cinnamon-session</b> implements the X Session Management Protocol (XSMP) to manage applications that comply with this standard, allowing them to save and restore their state across sessions, contributing to a more seamless user experience.


title: HISTORY
content:
<b>cinnamon-session</b> originates from the <b>gnome-session</b> project. When GNOME 3 introduced its new Shell interface, Linux Mint developers created Cinnamon as a fork of GNOME 3 technologies, aiming to provide a more traditional desktop experience. Consequently, <b>gnome-session</b> was forked and adapted to manage the Cinnamon desktop components, becoming <b>cinnamon-session</b>. This fork allowed Cinnamon to maintain its distinct desktop environment while leveraging the robust session management capabilities inherited from GNOME. Its development is tied to the evolution of the Cinnamon desktop environment by the Linux Mint team.


title: SYNOPSIS
content:
<i>cinnamon-session-properties</i><br>This command typically opens a graphical user interface (GUI) window and is primarily intended for interactive use. It does not commonly accept command-line arguments for its core functionality.


title: PARAMETERS
content:
<b><i>--help</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits. For <i>cinnamon-session-properties</i>, this usually shows generic GTK/application options rather than specific command-line functionality.<br><br><b><i>--version</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows the program's version information and exits.<br><br>


title: DESCRIPTION
content:
The <b>cinnamon-session-properties</b> command is a graphical utility within the Cinnamon desktop environment. It provides a user-friendly interface to manage applications that automatically start when a user logs into their Cinnamon session. Users can easily add new programs to launch at startup, remove existing ones, or modify the properties of autostart entries, including the command to be executed, its name, and a description. This tool is essential for customizing the user's desktop experience, streamlining their workflow, and optionally optimizing session startup times by controlling which applications load automatically. It serves as the Cinnamon-specific implementation of the functionality found in its GNOME predecessor, <i>gnome-session-properties</i>.


title: CAVEATS
content:
<ul><li>This command is a <b>graphical user interface (GUI)</b> application and requires a running Cinnamon desktop environment and an active display server (e.g., Xorg or Wayland) to function. It will not work in a purely text-based terminal session or on a server without a graphical display.</li><li>It primarily manages applications for the <b>current user's session only</b>. For system-wide services or applications that need to start before any user logs in, other tools like <i>systemctl</i> are used.</li><li>The configurations made through this utility are typically stored as XDG Desktop Entry Specification files (`.desktop` files) in the user's <i>~/.config/autostart/</i> directory. Direct manual editing of these files is an alternative but less user-friendly method.</li></ul>


title: ACCESSING FROM THE DESKTOP MENU
content:
In a typical Cinnamon desktop setup, <b>cinnamon-session-properties</b> can be conveniently launched without using the command line. It is usually accessible through the main menu by navigating to <i>Menu > Preferences > Startup Applications</i>, or a similar path depending on the distribution and menu layout.


title: CONFIGURATION FILES
content:
Changes made via <b>cinnamon-session-properties</b> are stored as individual `.desktop` files in the user's <i>~/.config/autostart/</i> directory. Each file defines a specific application to be launched at login, adhering to the XDG Desktop Entry Specification. This directory is the primary location for user-specific autostart configurations within XDG-compliant desktop environments.


title: HISTORY
content:
<b>cinnamon-session-properties</b> emerged as a direct descendant of the <i>gnome-session-properties</i> utility. When the Cinnamon desktop environment was created as a fork of GNOME Shell, many core components, including the session properties manager, were adapted to fit Cinnamon's specific libraries, design philosophy, and user experience. Its development trajectory has closely mirrored that of its GNOME predecessor, focusing on providing a stable and intuitive graphical interface for managing per-user startup applications within the Cinnamon ecosystem.


title: SEE ALSO
content:
gnome-session-properties(1): The equivalent tool in the GNOME desktop environment, from which Cinnamon forked., systemctl(1): A command-line utility for controlling the systemd system and service manager, used for system-wide services., xdg-autostart(7): Refers to the XDG Autostart Specification, which defines how desktop environments handle autostarting applications, implemented by tools like <i>cinnamon-session-properties</i>.


title: SYNOPSIS
content:
<i>cinnamon-session-quit</i> [--logout] [--power-off] [--reboot] [--halt] [--suspend] [--hibernate] [--hybrid-sleep] [--cancel] [--force]


title: PARAMETERS
content:
<b>--logout</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Logs out the current user session, returning to the display manager's login screen.<br><br><b>--power-off</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shuts down the system completely and powers off the hardware.<br><br><b>--reboot</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Restarts the system.<br><br><b>--halt</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Halts the system. On modern systems, this often has the same effect as --power-off.<br><br><b>--suspend</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Suspends the system to RAM (sleep mode), preserving the session state while consuming minimal power.<br><br><b>--hibernate</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Hibernates the system to disk, saving the session state and allowing the system to power off completely. Requires sufficient swap space.<br><br><b>--hybrid-sleep</b><br>&nbsp;&nbsp;&nbsp;&nbsp;A combination of suspend and hibernate; the session state is saved to both RAM and disk for resilience.<br><br><b>--cancel</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Cancels a pending session termination action that was initiated with a timeout (e.g., from a shutdown dialog).<br><br><b>--force</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces the requested action immediately, without waiting for applications to save or respond. Use with caution as unsaved data may be lost.<br><br>


title: DESCRIPTION
content:
<i>cinnamon-session-quit</i> is a command-line utility for the Cinnamon desktop environment, serving as the primary interface for managing a user's graphical session and initiating system power state changes. Its core function is to enable users to programmatically trigger a <b>logout</b> from their current desktop session, execute a full system <b>shutdown</b>, or perform a system <b>reboot</b>.<br><br>The command operates by communicating with the <i>cinnamon-session</i> daemon, which is the central process managing the Cinnamon desktop environment. This daemon, in turn, interacts with lower-level system services, notably <i>logind</i> (a component of <i>systemd</i>) or other power management mechanisms, to carry out the requested action. A key feature of <i>cinnamon-session-quit</i> is its attempt to gracefully terminate running applications, giving them a chance to save unsaved data and exit cleanly before the session or system is closed.


title: CAVEATS
content:
This command primarily operates within the context of a running Cinnamon user session. Power management actions (like suspend or hibernate) require underlying kernel support and proper system configuration (e.g., adequate swap space for hibernation). While <i>cinnamon-session-quit</i> initiates these actions, it delegates the actual system-level execution to services like <i>logind</i>, which may have specific user permission requirements or group memberships for full functionality.


title: GRACEFUL SESSION TERMINATION
content:
When invoked without the <i>--force</i> option, <i>cinnamon-session-quit</i> attempts to gracefully terminate running applications. It sends signals (e.g., <i>SIGTERM</i>) to applications, allowing them to perform cleanup operations, save data, and exit cleanly. If applications do not respond or take too long, the user might be prompted for a decision, or the action might be delayed until an explicit override is provided or a timeout occurs.


title: INTEGRATION WITH SYSTEMD/LOGIND
content:
On modern Linux distributions that utilize <i>systemd</i>, <i>cinnamon-session-quit</i> integrates seamlessly with the <i>systemd-logind</i> service via D-Bus. This integration is crucial for ensuring that system-wide power management actions (such as shutdown, reboot, suspend, and hibernate) are handled consistently and correctly by the operating system, rather than being confined solely to the desktop environment's scope. It allows for proper management of user sessions and secure system state transitions.


title: HISTORY
content:
The Cinnamon desktop environment was developed by Linux Mint as a fork of GNOME Shell, aiming to provide a more traditional and familiar desktop experience. Consequently, <i>cinnamon-session-quit</i> emerged from the design principles and core functionality established by <i>gnome-session-quit</i>, its counterpart in the GNOME environment. It serves the same purpose of session management, adapted to interact with the Cinnamon-specific session daemon (<i>cinnamon-session</i>), ensuring consistent and reliable session control within the Cinnamon ecosystem.


title: PARAMETERS
content:
<b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows version information and exits.<br><br><b><I>MODULE</I></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Opens a specific settings module directly. This allows users to jump straight to a particular section of the settings. Examples of common modules include: <I>applets</I>, <I>backgrounds</I>, <I>date-time</I>, <I>display</I>, <I>effects</I>, <I>extensions</I>, <I>network</I>, <I>sound</I>, <I>themes</I>, <I>users</I>, <I>windows</I>, <I>workspaces</I>.<br><br>


title: DESCRIPTION
content:
The <b>cinnamon-settings</b> command launches the graphical control center for the Cinnamon Desktop Environment. It provides a centralized interface for users to configure various aspects of their desktop experience, including appearance, hardware, system preferences, and personal settings. <br><br>Through a user-friendly interface, it organizes settings into logical categories such as Backgrounds, Applets, Themes, Network, Users, Display, Sound, and more, allowing for easy customization of the entire desktop environment. It's the primary tool for tailoring Cinnamon to individual user preferences without needing to directly edit configuration files.


title: CAVEATS
content:
<b>cinnamon-settings</b> is a graphical tool and requires a running Cinnamon desktop session to function properly. While it can be launched from the command line, its primary interaction is through a GUI. Settings changes made through this tool are typically applied immediately or upon next login, and are saved automatically. Direct command-line manipulation of settings beyond launching modules is generally not supported by this specific command.


title: MODULE NAVIGATION
content:
When launched without a <I>MODULE</I> argument, <b>cinnamon-settings</b> opens its main window, displaying categories of settings. Users can then navigate through these categories to find specific configuration options. Providing a <I>MODULE</I> argument directly bypasses the main window and opens the specified module, which is useful for automation or quick access.


title: HISTORY
content:
The <b>cinnamon-settings</b> utility is an integral part of the Cinnamon Desktop Environment, which was initially developed by Linux Mint in 2011 as a fork of GNOME Shell. Its creation was driven by a desire to provide a more traditional desktop experience with a modern aesthetic, contrasting with the direction taken by GNOME 3. <br><br>As Cinnamon evolved, <b>cinnamon-settings</b> was built to serve as its dedicated control center, distinct from the GNOME Control Center. It focuses on offering comprehensive configuration options specific to Cinnamon's unique features, such as applets, desklets, and extensions, while maintaining a user-friendly and intuitive interface that aligns with the desktop's overall design philosophy.


title: PARAMETERS
content:
<b><b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows a help message and exits.<br><br><b><b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows version information and exits.<br><br><b><b>--debug</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables verbose debug output to the console.<br><br><b><b>--replace</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Replaces a currently running instance of the daemon. Useful for restarting the daemon without logging out.<br><br>


title: DESCRIPTION
content:
<i>cinnamon-settings-daemon</i> is a crucial backend process for the Cinnamon desktop environment. It operates as a collection of plugins, each responsible for managing a specific aspect of the desktop's settings and functionality.<br><br>These include services like power management, keyboard and mouse input handling, display configuration, sound output, media key interpretation, and color management. It acts as the central hub for many user-configurable options, ensuring that changes made through the Cinnamon Settings application are applied system-wide and persist across sessions. The daemon typically starts automatically when a Cinnamon session begins and communicates with other desktop components via D-Bus, providing a robust and integrated settings management system for the user experience. Without <i>cinnamon-settings-daemon</i>, many core desktop features and settings would not function correctly.


title: CAVEATS
content:
If <i>cinnamon-settings-daemon</i> is not running or crashes, core desktop functionalities like power management, display settings, and keyboard layouts may cease to function correctly or be controllable. It's typically managed by the session manager and not intended for direct user invocation in normal operation.


title: PLUGINS ARCHITECTURE
content:
<i>cinnamon-settings-daemon</i> is built on a modular plugin architecture. Each plugin (e.g., responsible for power, keyboard, or media keys) runs within the daemon, allowing for extensible and manageable development of desktop functionalities. This design contributes to its stability and maintainability.


title: D-BUS INTEGRATION
content:
The daemon heavily relies on the D-Bus message bus system for inter-process communication. It exposes various D-Bus interfaces that other Cinnamon components and applications use to query and modify desktop settings, enabling a seamless and integrated user experience.


title: HISTORY
content:
The Cinnamon Desktop Environment, including <i>cinnamon-settings-daemon</i>, was created by Linux Mint in 2011 as a fork of GNOME 3. Consequently, <i>cinnamon-settings-daemon</i> is a direct descendant and fork of <i>gnome-settings-daemon</i>, inheriting much of its architecture and core functionality. Its development has since been tailored specifically for the Cinnamon environment, adapting to its unique features and requirements while maintaining compatibility with underlying system technologies.


title: PARAMETERS
content:
<b><b>-v</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays verbose information about each cipher, including protocol, key exchange, encryption, and message digest.<br><br><b><b>-V</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Shows very verbose information, including OpenSSL-specific internal IDs for each cipher.<br><br><b><b>-tls1_3</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Filters the output to only show cipher suites compatible with TLS 1.3.<br><br><b><b>-s</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists cipher suites in a format suitable for scripting or parsing, often used for configuration files.<br><br><b><b>-allow_broken</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Includes cipher suites known to be broken or insecure in the output. Use with extreme caution.<br><br><b><b>-std</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays cipher suite names using their standard IANA/RFC names, rather than OpenSSL's internal names.<br><br><b><b>-list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Explicitly requests a list of ciphers (this is the default behavior).<br><br><b><b><I>cipherlist</I></b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;A colon-separated string specifying criteria to filter and order the listed ciphers (e.g., <I>HIGH:!ADH:TLSv1.2</I>).<br><br>


title: DESCRIPTION
content:
The <b><I>openssl ciphers</I></b> command is a powerful utility within the OpenSSL toolkit, designed to display and manage cryptographic cipher suites. It allows users to list all available SSL/TLS cipher suites supported by their OpenSSL installation, filter them using a flexible colon-separated string format, and retrieve detailed information about each cipher. This tool is fundamental for system administrators and developers configuring and auditing the cryptographic security of applications that rely on SSL/TLS. By using <b><I>openssl ciphers</I></b>, one can ensure that only desired and secure cipher suites are enabled, helping to mitigate risks associated with weak or outdated cryptographic protocols. It provides insights into the various components of a cipher suite, such as the protocol version, key exchange method, authentication mechanism, encryption algorithm, and message digest function, which are crucial for maintaining robust network security.


title: CAVEATS
content:
The prompt refers to <I>ciphers.1s</I>, which is a common man page section reference, implying the command <I>openssl ciphers</I> found in section 1 of the OpenSSL manual. The actual command executed on a Linux system is <b><I>openssl ciphers</I></b>.<br>The list of supported ciphers and their details can vary significantly based on the installed OpenSSL version and its compile-time configuration.<br>Understanding the complex <I>cipherlist</I> string format requires familiarity with SSL/TLS terminology and OpenSSL's specific syntax.


title: CIPHER LIST STRING SYNTAX
content:
The <b><I>cipherlist</I></b> argument is a powerful and flexible colon-separated string used to filter and order cipher suites. It supports keywords like <I>HIGH</I>, <I>MEDIUM</I>, <I>LOW</I>, <I>DEFAULT</I>, <I>TLSv1.2</I>, <I>!aNULL</I>, <I>+SHA</I>, etc., allowing precise control over which ciphers are included or excluded based on their security properties, protocol versions, and algorithms. This syntax is common across various OpenSSL functions and configurations.


title: SECURITY BEST PRACTICES
content:
Utilizing <b><I>openssl ciphers</I></b> is crucial for implementing security best practices. It helps identify and disable weak or deprecated cipher suites (e.g., those using MD5, SHA1 for authentication, or short key lengths) and enforce the use of modern, strong ciphers (e.g., AES-GCM, ChaCha20-Poly1305 with TLS 1.2 or 1.3). Regular auditing of supported ciphers is recommended to adapt to the evolving threat landscape.


title: HISTORY
content:
The <b><I>openssl ciphers</I></b> command has been an integral part of the OpenSSL toolkit for many years, evolving alongside the SSL/TLS protocols themselves. Its development has consistently aimed to provide users with tools to inspect and manage cryptographic capabilities, adapting to new protocol versions (like TLS 1.2 and TLS 1.3) and addressing emerging security vulnerabilities in older ciphers. Its consistent presence and enhancements underline its critical role in the security hardening of network services.


title: SYNOPSIS
content:
<b>ciptool</b> <<i>command</i>> [<i>options</i>] [<i>arguments</i>]<br>Examples:<br><b>ciptool</b> <i>status</i><br><b>ciptool</b> <i>add</i> <<i>IB_device</i>><br><b>ciptool</b> <i>show</i> <<i>IB_device</i>>


title: PARAMETERS
content:
<b><i>status</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Displays the current status of all configured CIP devices.</i><br><br><b><i>add</i> <<i>IB_device</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Adds a new CIP device associated with the specified InfiniBand device (e.g., `ib0`).</i><br><br><b><i>del</i> <<i>IB_device</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Deletes an existing CIP device.</i><br><br><b><i>show</i> <<i>IB_device</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Shows detailed information and statistics for a specific CIP device.</i><br><br><b><i>set</i> <<i>IB_device</i>> <<i>parameter</i>> <<i>value</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Sets a specific parameter for a CIP device (e.g., `rate`, `mtu`).</i><br><br><b><i>-h</i>, <i>--help</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Displays help message and exits.</i><br><br><b><i>-V</i>, <i>--version</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Displays version information and exits.</i><br><br><b><i>-v</i>, <i>--verbose</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Increases verbosity of output.</i><br><br><b><i>-p</i>, <i>--port</i> <<i>port_num</i>></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<br><i>Specifies the InfiniBand port number to operate on (default usually 1).</i><br><br>


title: DESCRIPTION
content:
<b>ciptool</b> is a command-line utility for managing the <i>Common IP Interface</i> (CIP) on <i>InfiniBand</i> (IB) network adapters. CIP enables traditional IP networking over high-performance <i>InfiniBand</i> fabrics, bridging standard Ethernet/IP with <i>InfiniBand's</i> low-latency, high-bandwidth capabilities. This tool allows users to add, delete, show, and modify CIP devices, as well as inspect their operational status and statistics. It is typically used in environments where <i>InfiniBand</i> is deployed for high-performance computing (HPC) or data centers, often in conjunction with <i>RDMA</i>-enabled applications. <b>ciptool</b> provides granular control over how IP traffic is handled on these specialized interfaces, complementing standard network configuration tools.


title: CAVEATS
content:
<b>ciptool</b> requires specific <i>InfiniBand</i> hardware and drivers, commonly part of the <i>RDMA Core</i> or <i>OFED</i> distribution. It is not a standard utility found on all Linux systems and typically requires root privileges for configuration. While it manages IP over InfiniBand, the more common method, <i>IPoIB</i>, is often configured using standard `<b>ip</b>` or `<b>ifconfig</b>` commands after the <i>IPoIB</i> interface is brought up. <b>ciptool</b> is more specific to <i>CIP</i>-level features rather than general <i>IPoIB</i> setup.


title: IP OVER INFINIBAND (IPOIB) VS. CIP
content:
<i>While both enable IP networking over InfiniBand, <b>IPoIB</b> is the more prevalent method, presenting InfiniBand interfaces as standard network devices (e.g., `<b>ib0</b>`) configurable with typical IP tools. <b>CIP</b>, which <b>ciptool</b> manages, might refer to a more specialized or vendor-specific higher-level protocol or a distinct way of handling IP functionalities directly on the InfiniBand adapter. In many modern Linux setups, direct `<b>ip</b>` command usage for <b>IPoIB</b> is more common than direct <b>ciptool</b> usage for general IP configuration.</i>


title: HISTORY
content:
<b>ciptool</b> is part of the suite of utilities for <i>InfiniBand</i> devices, which have evolved alongside the <i>InfiniBand</i> specification itself. It's often included with vendor-specific <i>OFED</i> (<i>OpenFabrics Enterprise Distribution</i>) stacks and later integrated into the broader `<b>rdma-core</b>` userspace project. Its development is driven by the necessity for IP compatibility and specific configuration needs on <i>InfiniBand</i> fabrics, particularly in enterprise and HPC environments where this technology is critical for performance.


title: PARAMETERS
content:
<b>-T<format></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the output format. Common formats include 'png', 'svg', 'jpeg', 'pdf', 'ps'.<br><br><b>-o <file></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Writes the output to the specified file. If omitted, output goes to standard output (stdout).<br><br><b>-V</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Prints version information and exits.<br><br><b>-G<name>=<value></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a global graph attribute. For example, '-Gbgcolor=lightgrey'.<br><br><b>-N<name>=<value></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a default node attribute. For example, '-Nshape=circle'.<br><br><b>-E<name>=<value></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a default edge attribute. For example, '-Ecolor=blue'.<br><br><b>-s[<scale>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Scales the graph by the given factor. If no scale is given, it scales to fit the output page.<br><br><b>-y</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Inverts the y-coordinate in the output. Useful for systems with inverted y-axes.<br><br><b>-v</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables verbose mode, providing more detailed information during processing.<br><br><b>-L<level></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the logging level (0=none, 1=errors, 2=warnings, 3=info, 4=debug).<br><br>


title: DESCRIPTION
content:
The <b>circo</b> command is a layout engine from the <I>Graphviz</I> suite of open-source graph visualization software. It is specifically designed to produce <I>circular</I> or <I>radial</I> layouts of graphs, making it suitable for visualizing network topologies, phylogenetic trees, or any structure where nodes are arranged around a central point or in concentric circles. Unlike general-purpose layout algorithms that might spread nodes out in a grid or force-directed manner, circo attempts to position nodes on circles, often based on their connectivity or structural properties.<br><br>It takes graph descriptions written in the <I>DOT language</I> as input and outputs a graph in various formats, such as images (PNG, SVG, JPEG) or document formats (PDF, PostScript). It is part of a family of Graphviz layout engines, each optimized for different graph characteristics and visualization goals.


title: CAVEATS
content:
The <b>circo</b> command is not a standard standalone Linux utility but a specialized tool within the <I>Graphviz</I> package. It requires graph descriptions in the <I>DOT language</I> as input. If Graphviz is not installed, circo will not be available. Its primary function is graph layout, not general-purpose file processing.


title: USAGE WORKFLOW
content:
The typical workflow for using <b>circo</b> involves creating a graph description in the <I>DOT language</I> (usually in a file with a .dot extension), then processing it with circo to generate an output image or document. For example, consider a simple graph:<br><br><code>digraph G {<br>&nbsp;&nbsp;A -> B;<br>&nbsp;&nbsp;B -> C;<br>&nbsp;&nbsp;C -> A;<br>&nbsp;&nbsp;D -> A;<br>&nbsp;&nbsp;D -> E;<br>&nbsp;&nbsp;E -> F;<br>&nbsp;&nbsp;F -> D;<br>}</code><br><br>Save this content as <I>mygraph.dot</I>. To generate a PNG image with a circular layout, you would run:<br><br><code>circo -Tpng -o mygraph.png mygraph.dot</code><br><br>This command processes <I>mygraph.dot</I> using the circo layout engine and saves the resulting image to <I>mygraph.png</I>.


title: HISTORY
content:
<b>circo</b> is an integral part of the <I>Graphviz</I> project, which was initially developed at AT&T Labs Research for various graph drawing applications. Graphviz, including circo, has been under continuous development since the late 1990s, evolving to support diverse graph visualization needs. <b>circo</b> specifically addresses the demand for circular or radial graph layouts, offering a unique perspective compared to other algorithms like force-directed or hierarchical layouts.


title: SYNOPSIS
content:
<b>circup</b> [<i>global_options</i>] <i>command</i> [<i>arguments</i>]<br><br><u>Common Usage Examples:</u><br><b>circup</b> <i>install</i> <i>adafruit_motor</i><br><b>circup</b> <i>update</i><br><b>circup</b> <i>list</i><br><b>circup</b> <i>--path /media/CIRCUITPY</i> <i>install</i> <i>adafruit_displayio</i>


title: PARAMETERS
content:
<b><i>command</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The specific action to perform. See subcommands below for details.<br><br><b><b>install</b> <i>&lt;library&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Installs the specified <i>CircuitPython</i> library (or libraries, space-separated) onto the connected device. Can also accept `requirements.txt` style input via `--input-requirements`.<br><br><b><b>uninstall</b> <i>&lt;library&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Removes the specified <i>CircuitPython</i> library (or libraries, space-separated) from the connected device.<br><br><b><b>update</b> [<i>&lt;library&gt;</i>]</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Updates all installed <i>CircuitPython</i> libraries to their latest compatible versions. If a <i>library</i> name is specified, only that library will be updated.<br><br><b><b>list</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists all <i>CircuitPython</i> libraries currently installed on the connected device.<br><br><b><b>freeze</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Lists installed <i>CircuitPython</i> libraries and their versions, along with compatible libraries from the current bundle, similar to `pip freeze`.<br><br><b><b>search</b> <i>&lt;query&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Searches for <i>CircuitPython</i> libraries matching the specified <i>query</i> in the available bundles.<br><br><b><b>show</b> <i>&lt;library&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays detailed information about a specific <i>CircuitPython</i> library.<br><br><b><b>bundle</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays information about the current <i>CircuitPython</i> library bundle being used by <b>circup</b>.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a help message and exits. Can be used globally or with subcommands (e.g., `circup install --help`).<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the program's version number and exits.<br><br><b><b>--path</b> <i>&lt;path&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the mount point of the <i>CircuitPython</i> device (e.g., <i>/media/CIRCUITPY</i>) if auto-detection fails.<br><br><b><b>--target-board</b> <i>&lt;board_name&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the target board name (e.g., `feather_m4_express`) to ensure library compatibility.<br><br><b><b>--input-requirements</b> <i>&lt;file&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Reads a newline-separated list of library names from the specified <i>file</i> to install or update.<br><br><b><b>--output-requirements</b> <i>&lt;file&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Writes a list of currently installed libraries to the specified <i>file</i>, similar to a `pip` requirements file.<br><br><b><b>--auto-update</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Automatically updates <b>circup</b> itself to the latest version before running the requested command.<br><br><b><b>--skip-version-check</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Skips checking if the <b>circup</b> tool itself is out of date.<br><br><b><b>--json</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Outputs command results in JSON format, useful for scripting or parsing.<br><br><b><b>--usb-device-id</b> <i>&lt;id&gt;</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Connects to a specific USB device ID, useful when multiple CircuitPython boards are connected.<br><br><b><b>--pretend</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Performs a dry run, showing what changes would be made without actually modifying the device.<br><br>


title: DESCRIPTION
content:
<b>circup</b> is a specialized command-line utility built with Python, designed for efficient management of libraries on <i>CircuitPython</i>-enabled microcontroller boards. These boards include popular options like Adafruit Feathers, ESP32s, and Raspberry Pi Picos.<br><br>The primary function of <b>circup</b> is to simplify the process of installing, updating, uninstalling, and listing <i>CircuitPython</i> libraries directly on the connected device's `CIRCUITPY` drive. It acts as a bridge between the host computer and the microcontroller, ensuring that the necessary libraries are available and up-to-date for your embedded projects.<br><br>It can fetch libraries from the official <i>CircuitPython</i> library bundle, specified URLs, or local paths. This tool is indispensable for developers working with <i>CircuitPython</i>, helping to manage dependencies, ensure compatibility, and streamline the development workflow by providing a robust and easy-to-use interface for library management.


title: CAVEATS
content:
<b>circup</b> is not a core Linux utility but a Python application. It requires Python and `pip` to be installed on the host system. It also relies on a <i>CircuitPython</i> device being connected via USB and properly mounted as a mass storage device (typically named `CIRCUITPY`). Permissions issues, particularly with USB device access (e.g., `udev` rules on Linux), can prevent <b>circup</b> from functioning correctly. An active internet connection is usually required to download libraries from the <i>CircuitPython</i> bundle.


title: INSTALLATION
content:
To use <b>circup</b>, you must first install it on your host system using <b>pip</b>, Python's package installer:<br><code><b>pip install circup</b></code><br>It's recommended to install it within a Python virtual environment to avoid conflicts with system-wide packages.


title: CIRCUITPYTHON ECOSYSTEM
content:
<b>circup</b> is an integral part of the larger <i>CircuitPython</i> ecosystem, a Python implementation for microcontrollers. It exclusively manages libraries specifically designed for <i>CircuitPython</i>, which are often optimized for low-memory environments and hardware interaction.


title: HISTORY
content:
<b>circup</b> was developed by <i>Adafruit Industries</i> as an essential tool for their <i>CircuitPython</i> ecosystem. Its inception aimed to streamline the often cumbersome process of managing external libraries on memory-constrained microcontroller devices. Since its initial release, it has undergone continuous development, with regular updates and improvements, making it a robust and widely used utility within the <i>CircuitPython</i> community. It's maintained as an open-source project on GitHub.


title: PARAMETERS
content:
<b><B>-quality N</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Set the compression quality factor to N (0-100). Higher values yield better quality but larger files.</I><br><br><b><B>-optimize</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Perform optimization of Huffman coding tables. This usually results in slightly smaller files but takes longer.</I><br><br><b><B>-progressive</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Create a progressive JPEG file. Progressive JPEGs display a low-resolution version first, then gradually improve detail.</I><br><br><b><B>-baseline</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Force creation of a baseline JPEG file (the default for most JPEGs). This ensures maximum compatibility.</I><br><br><b><B>-grayscale</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Create a grayscale JPEG file, discarding color information.</I><br><br><b><B>-fastcrush</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Use a faster, but slightly less effective, algorithm for Huffman table selection. Often used with <B>-optimize</B>.</I><br><br><b><B>-outfile filename</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Specify the output JPEG file name. If omitted, output is sent to standard output.</I><br><br><b><B>-arithmetic</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Use arithmetic coding instead of Huffman coding. This is less common due to patent issues and slower performance, though it can yield slightly smaller files.</I><br><br><b><B>-idct METHOD</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Specify the IDCT (Inverse Discrete Cosine Transform) algorithm to use. Methods include <B>int</B> (integer), <B>simple</B> (simple integer), <B>fast</B> (fast integer), <B>float</B> (floating point).</I><br><br><b><B>-color</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Specify the input color space. Common options include <B>rgb</B>, <B>cmyk</B>, <B>ycck</B>.</I><br><br><b><B>-restart N</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Add N-sample restart markers to the JPEG stream. This improves error resilience and allows for partial decoding.</I><br><br><b><B>-smooth N</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Perform an N-point smoothing of the input image before compression. (Requires <B>libjpeg-turbo</B>).</I><br><br><b><B>-maxmemory N</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Set the maximum memory to use in kilobytes for image processing.</I><br><br><b><B>-verbose</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Print more information about the compression process, including progress and statistics.</I><br><br><b><B>-version</B></b><br>&nbsp;&nbsp;&nbsp;&nbsp;<I>Print the <B>cjpeg</B> version number and exit.</I><br><br>


title: DESCRIPTION
content:
<I>The <B>cjpeg</B> command is a utility from the Independent JPEG Group (IJG) JPEG library, often distributed as part of <B>libjpeg-turbo</B> or <B>mozjpeg</B>. Its primary function is to convert various image formats, such as PPM, PGM, BMP, and TGA, into the highly compressed JPEG format. <B>cjpeg</B> applies lossy compression, which means some image data is discarded to achieve smaller file sizes, particularly useful for web graphics and storage. Users can control the compression quality, optimize Huffman tables, and select various encoding modes like progressive or baseline JPEG. It is a fundamental tool for preparing images for scenarios where file size efficiency is crucial.</I>


title: CAVEATS
content:
<I><br>• <B>Lossy Compression:</B> JPEG is a lossy format. Each time an image is saved in JPEG format (especially at lower qualities), some data is permanently lost. Repeated re-compression of JPEGs can lead to significant visual degradation.<br>• <B>Quality Trade-offs:</B> Balancing file size and visual quality is crucial. Very low quality settings (e.g., below 50) often result in noticeable compression artifacts.<br>• <B>Color Space Handling:</B> Incorrect handling of color spaces (e.g., RGB vs. CMYK) can lead to undesirable color shifts or incorrect rendering in the output.<br>• <B>Arithmetic Coding:</B> While potentially offering slightly better compression, arithmetic coding is rarely used due to historical patent issues and slower processing times. It's also not universally supported by all JPEG decoders.<br>• <B>Input Formats:</B> <B>cjpeg</B> typically only accepts raw image formats like PPM, PGM, BMP, or TGA. It cannot directly compress common formats like PNG or TIFF; these must be converted first.</I>


title: <B>SUPPORTED INPUT FORMATS</B>
content:
<I><B>cjpeg</B> primarily accepts raw image formats such as Portable PixMap (<B>.ppm</B>), Portable GrayMap (<B>.pgm</B>), Windows Bitmap (<B>.bmp</B>), and Truevision TGA (<B>.tga</B>). It does not directly read more complex formats like PNG or TIFF. Users typically convert these formats to PPM/PGM first before feeding them to <B>cjpeg</B>.</I>


title: <B>DEFAULT OUTPUT</B>
content:
<I>By default, <B>cjpeg</B> writes the resulting JPEG data to standard output. This allows for piping its output to other commands or redirecting it to a file using shell redirection (e.g., <B>cjpeg input.ppm &gt; output.jpg</B>). The <B>-outfile</B> option provides an alternative for direct file output.</I>


title: HISTORY
content:
<I><B>cjpeg</B> originated as part of the Independent JPEG Group's (IJG) reference implementation of the JPEG standard. The IJG library (<B>libjpeg</B>) became the de facto standard for JPEG encoding and decoding on Unix-like systems. Over time, several highly optimized forks and implementations emerged, most notably <B>libjpeg-turbo</B> (focused on speed using SIMD instructions) and <B>mozjpeg</B> (focused on achieving even smaller file sizes at high quality settings, often used for web optimization). <B>cjpeg</B> remains a core component of these distributions, providing a command-line interface to their powerful JPEG compression capabilities.</I>


title: PARAMETERS
content:
<b>-d, --distance <i>NUM</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets the target Butteraugli distance for lossy compression. 0 for lossless. Higher values mean more compression, lower quality. (Default: 1.0)<br><br><b>-q, --quality <i>NUM</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Sets a JPEG-like quality setting (0-100). Correlates with <i>--distance</i> but is more user-friendly. Higher values mean better quality.<br><br><b>-e, --effort <i>NUM</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Controls the encoding effort/speed (1=fastest, 9=slowest/best compression). Higher effort yields smaller files but takes longer. (Default: 7)<br><br><b>-s, --speed <i>NUM</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Alias for <i>--effort</i>.<br><br><b>--modular</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces modular mode (lossless encoding). Useful for synthetic images or when <i>--distance</i> is 0.<br><br><b>--container</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Forces the use of the JXL container format, which enables features like animations or embedded JPEG bitstreams.<br><br><b>--jpeg_recompress</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Losslessly recompress a JPEG file to JXL. The original JPEG bitstream is optionally embedded for backward compatibility.<br><br><b>--num_threads <i>NUM</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the number of threads to use for encoding. (Default: based on CPU cores)<br><br><b>-h, --help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays help message and exits.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays version information and exits.<br><br>


title: DESCRIPTION
content:
The <b>cjxl</b> command is the official command-line encoder for the new JPEG XL (JXL) image format. JPEG XL is a royalty-free, next-generation image coding system designed for superior compression efficiency and rich functionality. <b>cjxl</b> converts various input image formats (e.g., PNG, JPEG, GIF, PPM, TIFF) into highly optimized JXL files. It supports both lossy and lossless compression modes, allowing users to balance file size with image fidelity. Key features include support for animated images, progressive decoding, and the ability to losslessly recompress existing JPEG files into JXL, potentially reducing their size without quality loss while maintaining the original JPEG data within the JXL stream for backward compatibility. Its versatility makes it suitable for web delivery, photography, and archival purposes.


title: CAVEATS
content:
Encoding with <b>cjxl</b>, especially at higher <i>--effort</i> settings, can be computationally intensive and time-consuming. While JPEG XL generally offers superior compression at high qualities, for very low-detail images at extremely low target sizes, older formats might occasionally yield smaller files or faster encoding. Browser and software support for JPEG XL is growing but might not be universal yet.


title: INPUT/OUTPUT FORMATS
content:
<b>cjxl</b> accepts a wide range of input image formats including PNG, JPEG, GIF, PPM, and TIFF. The output is always a JPEG XL file with the <i>.jxl</i> extension. It can also handle multi-frame inputs for animation encoding.


title: LOSSY VS. LOSSLESS
content:
By default, <b>cjxl</b> operates in a lossy mode optimized for perceptual quality using the Butteraugli metric (controlled by <i>--distance</i>). Setting <i>--distance 0</i> or using the <i>--modular</i> option forces lossless compression, ensuring no data is discarded.


title: HISTORY
content:
JPEG XL (JXL) is a modern, royalty-free image format developed by the Joint Photographic Experts Group (JPEG) committee. Its development began in 2017, and it was officially standardized as ISO/IEC 18181 in October 2021. The <b>cjxl</b> encoder is part of the reference implementation library, <i>libjxl</i>, which was designed to be highly optimized and serve as a successor to legacy image formats like JPEG, PNG, and GIF, aiming to provide better compression and more features.


title: SYNOPSIS
content:
<b>ckbcomp</b> [<b>-o</b> <i>OUTPUT_FILE</i>] [<b>-d</b>] [<b>-h</b>] [<b>-v</b>] <i>INPUT_FILE.ckbl</i>


title: PARAMETERS
content:
<b><i>INPUT_FILE.ckbl</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;The path to the input keyboard layout file to be compiled. This file typically has a <i>.ckbl</i> extension and contains definitions for key assignments, lighting, and macros.<br><br><b><b>-o</b> <i>OUTPUT_FILE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Specifies the path for the compiled output file. If this option is not provided, <b>ckbcomp</b> may output to a default location or standard output, depending on the specific implementation. The output file typically has a <i>.ckbc</i> extension.<br><br><b><b>-d</b>, <b>--debug</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Enables verbose debug output during the compilation process. This can be particularly useful for troubleshooting syntax errors or unexpected behavior within the input layout file.<br><br><b><b>-h</b>, <b>--help</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays a brief help message detailing the command usage and available options, then exits.<br><br><b><b>-v</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Displays the version information of the <b>ckbcomp</b> utility, then exits.<br><br>


title: DESCRIPTION
content:
<b>ckbcomp</b> is a utility provided by the <i>ckb-next</i> project, a Linux driver for Corsair RGB peripherals. Its primary function is to compile custom keyboard layout files, typically with a <i>.ckbl</i> extension, into a binary format (<i>.ckbc</i>) that the <i>ckb-next</i> daemon can interpret and load. This process allows users to define custom key assignments, lighting effects, and macros for their Corsair keyboards. The command also performs syntax checking on the input layout files, ensuring they are correctly formatted before compilation. It is an essential tool for advanced customization of Corsair RGB devices under Linux, enabling tailored user experiences beyond default configurations.


title: CAVEATS
content:
<b>ckbcomp</b> is specifically designed for compiling layout files used by the <i>ckb-next</i> open-source driver for Corsair RGB peripherals. The compiled files (<i>.ckbc</i>) are not standalone and require the <i>ckb-next</i> daemon to be running on a Linux system to be loaded and applied to the hardware. Users must ensure their <i>.ckbl</i> input files strictly adhere to the specific syntax defined by the <i>ckb-next</i> project for successful compilation.


title: LAYOUT FILE SYNTAX
content:
The <i>.ckbl</i> layout files processed by <b>ckbcomp</b> follow a specific declarative syntax. Users should refer to the official <i>ckb-next</i> project documentation and examples for detailed information on how to write these files, including definitions for key mappings, intricate lighting zones, and complex macro programming.


title: INTEGRATION WITH CKB-NEXT
content:
After a layout file is successfully compiled by <b>ckbcomp</b> into a <i>.ckbc</i> binary, it must then be loaded by the <i>ckb-next</i> daemon to take effect on the connected Corsair device. This loading process is typically managed using the <i>ckb-cli</i> command-line tool or through the graphical user interface provided by the <i>ckb-next</i> suite, allowing for immediate application of custom layouts.


title: HISTORY
content:
<b>ckbcomp</b> is an integral component of the open-source <i>ckb-next</i> project, which began development to address the lack of official Linux support for Corsair RGB keyboards and mice. As Corsair peripherals gained popularity, <i>ckb-next</i> provided a crucial solution for Linux users, and <b>ckbcomp</b> became essential for enabling deep customization of these devices through custom layout compilation. Its development is tied directly to the evolution and maintenance of the <i>ckb-next</i> driver itself, continuously improving support and features for Corsair hardware on Linux.


title: PARAMETERS
content:
<b>FILE</b><br>&nbsp;&nbsp;&nbsp;&nbsp;One or more files to be checksummed. If no <i>FILE</i> is specified, or if <i>FILE</i> is '-', <b>cksum</b> reads from standard input.<br><br><b>--help</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Display a help message and exit.<br><br><b>--version</b><br>&nbsp;&nbsp;&nbsp;&nbsp;Output version information and exit.<br><br>


title: DESCRIPTION
content:
The <b>cksum</b> command computes a Cyclic Redundancy Check (CRC) checksum for each specified file and displays the checksum, the number of bytes in the file, and the filename.<br><br>It is primarily used to detect accidental data corruption during transmission or storage. By comparing the <b>cksum</b> output of a file at different times or locations, users can verify its integrity.<br><br>The algorithm used is a 32-bit CRC, specified by POSIX, which makes it standardized across different Unix-like systems. For each file, <b>cksum</b> prints a line containing the calculated checksum, the file size in bytes, and the original filename. If no files are specified, it reads from standard input.<br><br>It's important to note that <b>cksum</b> is <i>not</i> cryptographically secure. It is suitable for detecting random errors but cannot protect against deliberate tampering, as collisions (different files producing the same checksum) can be found relatively easily. For strong cryptographic integrity checks, commands like <b>md5sum</b> or <b>sha256sum</b> should be used.


title: CAVEATS
content:
<b>cksum</b> is <i>not</i> cryptographically secure. It is designed to detect <i>accidental</i> data corruption, not malicious tampering. Collisions (different data producing the same checksum) are relatively easy to find.<br><br>While the CRC-32 algorithm is specified by POSIX, subtle variations in implementation (e.g., polynomial, initial value, XOR output) can theoretically exist, though for the `cksum` utility as part of GNU Core Utilities, it's generally consistent.


title: OUTPUT FORMAT
content:
For each input <i>FILE</i>, <b>cksum</b> outputs a single line in the format: <code>CHECKSUM SIZE FILENAME</code>.<br><br>When reading from standard input, <i>FILENAME</i> is replaced by a hyphen (<code>-</code>).<br><br>Example: <code>cksum <i>myfile.txt</i></code> might output <code>3810234567 1234 <i>myfile.txt</i></code>, where <code>3810234567</code> is the checksum and <code>1234</code> is the file size in bytes.


title: COMMON USE CASES
content:
<ul><li>Verifying file integrity after downloading: Compare the checksum provided by the source with the one computed locally.</li><li>Checking for accidental changes in configuration files or other critical data.</li><li>Simple data validation within scripts or automated processes.</li></ul>


title: HISTORY
content:
The <b>cksum</b> command is part of the GNU Core Utilities and is standardized by POSIX.1-2001 and later versions. It evolved from earlier Unix <b>sum</b> commands to provide a more portable and consistent checksum calculation across different Unix-like systems. Its primary advantage over the older <b>sum</b> command was the standardization of the 32-bit CRC algorithm, ensuring that the same file would yield the same checksum result on different compliant systems.


title: PARAMETERS
content:
<b><b>-r</b>, <b>--recursive</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Scan directories recursively.<br><br><b><b>-i</b>, <b>--infected</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Only print infected files. Suppresses output for clean files.<br><br><b><b>--remove</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Remove infected files. <i>Use with extreme caution</i> as this irrevocably deletes files.<br><br><b><b>--move=</b><i>DIRECTORY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Move infected files to the specified directory.<br><br><b><b>--copy=</b><i>DIRECTORY</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Copy infected files to the specified directory.<br><br><b><b>--log=</b><i>FILE</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Log scan results to the specified file.<br><br><b><b>--stdout</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Print scan results to standard output.<br><br><b><b>--bell</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Ring the bell on virus detection.<br><br><b><b>-v</b>, <b>--verbose</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Be verbose during scanning, showing more details.<br><br><b><b>--exclude=</b><i>REGEX</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Exclude files or directories matching the regular expression.<br><br><b><b>--include=</b><i>REGEX</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Only include files or directories matching the regular expression.<br><br><b><b>--database=</b><i>FILE/DIR</i></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Load virus definitions from the specified file or directory instead of the default location.<br><br><b><b>-V</b>, <b>--version</b></b><br>&nbsp;&nbsp;&nbsp;&nbsp;Print the ClamAV version number and exit.<br><br>


