xwininfo

Display a cursor to select a window to display its attributes (id, name, size, position, ...)

$ xwininfo

$ xwininfo -tree -root

$ xwininfo -id [id]

$ xwininfo -name [name]

$ xwininfo -tree -root | grep [keyword] | head -1 | perl -ne 'print $1 if /(0x[\da-f]+)/ig;'

xwininfo [-help] [-int] [-display dpy] [-id id] [-root] [-name name] [-tree] [-stats] [-bits] [-events] [-size] [-font] [-wm] [-all]

-help
    Print brief usage summary and exit.


-int
    Display integer values (IDs, coordinates) in decimal, hexadecimal, and octal.


-display dpy
    Connect to specified X display (e.g., :0).


-id id
    Use specific hexadecimal window ID instead of picking.


-root
    Target the screen's root window.


-name name
    Select top-level window by exact resource name.


-tree
    Show window ID tree from target window down.


-stats
    Print window enter/leave event counts.


-bits
    Show bit gravity, backing-store, and save-under flags.


-events
    List subscribed event masks.


-size
    Display normal and zoom size hints.


-font
    Print font name hierarchy for window.


-wm
    Show window manager hints.


-all
    Print all available information categories.

xwininfo is a utility from the X Window System toolkit that provides detailed information about windows managed by the X server. When invoked without specifying a window ID, it enters "pick" mode, allowing the user to click on any visible window to retrieve its properties. Output includes essential details such as the window ID, geometry (position and size), class, resource name, parent window, and more, depending on selected options.

It is invaluable for X11 developers, system administrators, and users debugging graphical applications. For instance, it reveals window manager hints, event masks, font hierarchies, and size constraints. By combining options like -tree or -all, users can explore the window hierarchy or get comprehensive data.

Typically used in X11 environments (not native to Wayland), it requires a valid $DISPLAY variable. Common use cases include scripting window manipulations, verifying window attributes in test suites, or identifying problematic windows causing display issues. The tool outputs human-readable text, making it suitable for parsing in shell scripts with tools like grep or awk.

Does not work natively on Wayland; use XWayland if available. Pick mode captures only visible windows. Window names must match exactly with -name. Requires X11 permissions and $DISPLAY set.

Basic pick: xwininfo → Click window.
Root info: xwininfo -root
All details: xwininfo -id 0x123456 -all
Tree view: xwininfo -tree

Introduced in X Version 11 Release 4 (X11R4) around 1989 by the MIT X Consortium. Maintained in Xorg project since XFree86 fork; current versions in xorg-x11-utils package.

xprop(1), xdpyinfo(1), xprop(1), wmctrl(1)