xdpyinfo

xdpyinfo [-display display] [-auth authorization] [-geometry] [-extend] [-ext extension] [-queryExtensions] [-all] [-screen number] [-visual visualid] [-version]

-display display
    Specify X display (default: $DISPLAY)

-auth authorization
    Specify authorization file for X server access

-geometry
    Print window geometry hints supported by window manager

-extend
    Print extended, detailed information about display

-ext extension
    Print information only for specified extension

-queryExtensions
    List all extensions supported by the server

-all
    Print all available information

-screen number
    Restrict output to specific screen number

-visual visualid
    Print details for specific visual ID

-version
    Print version information and exit

xdpyinfo is a diagnostic utility in the X11 Window System that queries and prints detailed information about an X display server. It reveals configuration details such as screen dimensions, resolutions, color depths, available visuals, font paths, supported extensions, and server vendor information.

Primarily used by developers, system administrators, and users troubleshooting graphical issues, xdpyinfo helps verify X server capabilities, identify supported protocols, and inspect display properties without needing graphical tools. For instance, it lists all loaded extensions like XFree86-VidMode or RANDR, which manage screen resizing and rotation.

Output is structured into sections: version, screen details (width, height, root window), depths (pixel depths supported), visuals (color models like TrueColor or DirectColor), and more. When run with -all, it provides exhaustive data; otherwise, it defaults to basic screen info. It's lightweight, non-interactive, and outputs plain text parseable by scripts for automation.

Essential for X11 environments, it's absent or incompatible in Wayland compositors, highlighting its X11-specific nature.

Only functions with X11 servers; incompatible with Wayland. Requires read access to X server. Verbose output can be overwhelming without options.

Includes: version, vendor string, screen info (dimensions, white/black points), depths, visuals, pixmaps, rgb, font path, extensions list.
Example: name of display: :0
version number: 11.0

Run xdpyinfo | grep -i 'extensions:' to list extensions; xdpyinfo -ext RANDR for specific details.

Developed as part of the X Window System by the MIT X Consortium in the 1980s. Maintained by X.Org Foundation since 2004, with versions tracking X11 releases (e.g., X11R7). Widely used in Unix-like systems for decades.

xwininfo(1), xprop(1), xrandr(1), xdriinfo(1), xset(1)