Getting a window's PID by clicking on it

Question

Is there any package which shows PID of a window by clicking on it?

Answer 1

Yes. Try xprop and you are looking for the value of _NET_WM_PID:

xprop _NET_WM_PID | cut -d' ' -f3
{click on window}

Answer 2

xprop will return a window's PID.

You can filter the verbose output using awk:

xprop | awk '/PID/ {print $3}'

Answer 3

To complete those excellent answers, here is a little bash command to get the command (that I actually needed):

id=`xprop _NET_WM_PID | awk '/PID/ {print $3}'`; cat /proc/$id/comm

Example:

Lila ~ # id=`xprop _NET_WM_PID | awk '/PID/ {print $3}'`; cat /proc/$id/comm

gnome-terminal-