xkbcomp

xkbcomp [-w level] [-o file] [-R directory] [source files] [target device]

source files typically refer to XKB definition files or references to configurations (e.g., 'xkbmap :0' to get the current map from the server).
target device specifies where the compiled map should be sent. This is commonly an X display (e.g., :0) to load the map, or xkb to print the compiled source to standard output, or file to output to a binary file.

-w level
    Sets the warning level for the compiler. Higher levels (e.g., 10) provide more verbose warning messages during compilation.

-o file
    Specifies the output file where the compiled XKB map will be written. If omitted, the output may be directed to the specified target device or standard output.

-R directory
    Overrides the default root directory for XKB configuration files. This specifies where xkbcomp should begin searching for XKB definitions.

-I directory
    Adds a specified directory to the list of paths that xkbcomp searches when resolving included XKB files.

-v level
    Sets the verbosity level for compiler messages. A higher level results in more detailed output, useful for debugging.

-xkbmap file
    Instructs xkbcomp to load the specified file directly as an XKB map description.

-p (or -print)
    Causes xkbcomp to print the compiled XKB map source (in its textual representation) to standard output, rather than loading it onto an X server or writing it to a file.

-help
    Displays a brief summary of command-line options and usage information.

xkbcomp is a crucial utility in the X Window System that compiles XKB (X Keyboard Extension) keyboard description files into a binary format. This binary representation can then be loaded and interpreted by an X server or other XKB-aware applications.

The XKB system offers a powerful and flexible method for defining intricate keyboard layouts, including symbols, keymaps, and various behavioral aspects. It greatly surpasses older keyboard configuration tools like xmodmap by supporting features such as multiple keyboard groups, dead keys, sticky keys, and complex modifier handling. xkbcomp is the core component that processes the human-readable text files (which detail rules, layouts, symbols, types, and compatibility maps) and translates them into the optimized binary data essential for the X server to manage all keyboard input.

Configuring XKB can be intricate due to its highly customizable and modular structure. Issues often arise from incorrect file paths, syntax errors in XKB definition files, or conflicts between different components (e.g., rules, symbols, types). An improperly compiled XKB map can lead to a non-functional or incorrectly behaving keyboard within the X session.

XKB configuration files are typically organized into a hierarchical directory structure, commonly found in /usr/share/X11/xkb/ or /etc/X11/xkb/. This includes subdirectories for 'rules', 'layouts', 'symbols', 'geometry', and 'types'. xkbcomp reads and merges these individual components to form a complete keyboard description.

One of the most common uses of xkbcomp is to apply a new keyboard map directly to a running X display. For instance, the command 'xkbcomp my_layout.xkb :0' would compile the my_layout.xkb file and immediately load the resulting keyboard map onto the X server running on display :0.

The X Keyboard Extension (XKB) was introduced in the early 1990s as a sophisticated replacement for the simpler, less flexible xmodmap utility. It aimed to provide comprehensive support for international keyboard layouts, dead keys, and complex modifier interactions within the X Window System. xkbcomp has been fundamental to the XKB system since its inception, acting as the compiler that translates human-readable XKB definitions into the optimized binary format consumed by the X server. Its development has closely paralleled the evolution of X11 and its increasing demand for advanced keyboard handling.

setxkbmap(1), xmodmap(1), X(7), Xorg(1)