Introduction

wpid-by-wid is program which outputs a PID for a given X Window ID.

This tool serves the same purpose as xdotool getwindowpid [id] except that wpid-by-wid is more precise; while xdotool only inspects _NET_WM_PID, which might unset for a given window or perhaps set incorrectly, wpid-by-id first searches the PID by using the XRes extension, only falling back to _NET_WM_PID in case the former somehow doesn't work (we expect it to always work).

Installing

First build the application by running ./build. A ./wpid-by-wid executable will be compiled from that command, which you can then run as:

wpid-by-wid [window_id]

The [window_id] argument is given in decimal (e.g. 123, base 10) or hexadecimal (e.g. 0xffffff, base 16). You're able to figure out the window ID of a given application through a variety of ways such as $WINDOWID, xprop, xwininfo, wmctrl -l, window manager events, X events, etcetera.

References

• https://github.com/freedesktop/xorg-xwininfo
• https://stackoverflow.com/questions/52986307/x11-get-the-list-of-main-windows-using-xcb
• https://gitlab.gnome.org/GNOME/metacity/-/merge_requests/13/diffs