Find out the application under the mouse

Question

It often happens to me, that an application pops up a question and I wonder to which exact application this window belongs, because if I look in the Launcher there is no application that currently has focus (no white triangle on the right side of the icon when I focus the message window)

Is there a way to find out the belonging of an open window?

Answer 1

Using xdotool

First make sure xdotool is available on your system:

sudo apt-get install xdotool

The following command will print the process name of the window currently in focus:

cat "/proc/$(xdotool getwindowpid "$(xdotool getwindowfocus)")/comm"

To give yourself more time to focus the window / click on it you can prepend a small sleep duration:

sleep 5 && cat "/proc/$(xdotool getwindowpid "$(xdotool getwindowfocus)")/comm"

The process name should be displayed after a short amount of time.

---

Using wininfo

Wininfo is a graphical utility that displays various information on windows and their properties, including the PID (process ID) associated with the window:

wininfo should be available in the official repositories:

sudo apt-get install wininfo

---

Having determined the PID of the window you can then look up the process name associated with it. There are various ways to do this, e.g. by looking at /proc:

$ cat /proc/17002/comm
gnome-terminal

This would be the process name associated with the PID 17002.

A more elegant way that allows inspecting the process tree context, as suggested by @Rmano:

$ pstree -a -s -l -p -u 17002
init,1
  └─lightdm,1900
      └─lightdm,3202 --session-child 12 19
          └─lxsession,3307,glutanimate -s LXDE -e LXDE
              └─openbox,3362 --config-file /home/glutanimate/.config/openbox/lxde-rc.xml
                  └─gnome-terminal,17002
                      ├─bash,1841
                      ├─bash,2332
                      ├─bash,2424
                      │   └─pstree,2484 -a -s -l -p -u 17002
                      ├─gnome-pty-helpe,1840
                      ├─{gnome-terminal},1835
                      ├─{gnome-terminal},1836
                      ├─{gnome-terminal},1842
                      └─{gnome-terminal},2269

Of course you can also combine pstree with the xdotool option above (thanks to @rubo77 for pointing this out!):

sleep 2; pstree -spaul $(xdotool getwindowpid "$(xdotool getwindowfocus)")

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Sources:

https://unix.stackexchange.com/q/38867/29245

http://www.linuxquestions.org/questions/debian-26/how-to-find-the-process-associated-with-a-top-level-x-window-907125/

https://superuser.com/q/632979/170160

Answer 2

You can create a keyboard-shortcut with this command:

zenity --info --text $(xprop $win_id WM_CLASS | cut -d" " -f4-)

Answer 3

You can use xprop to get the Process ID of the clicked Window:

xprop $win_id _NET_WM_PID

then analyze it with pstree:

pstree -spaul $(xprop $win_id _NET_WM_PID | cut -d" " -f3-)

This you can redirected to a text-info window with

pstree -spaul $(xprop $win_id _NET_WM_PID | cut -d" " -f3-)|zenity --text-info --title "pstree of clicked Window"

I tried to create a keyboard-shortcut for this last command (if you need it regularely), but for some reason This doesn't work.

Answer 4

With xdtool and yad installed you can have a nice GUI App.

#!/bin/bash
while true; do cat "/proc/$(xdotool getwindowpid "$(xdotool 
getwindowfocus)")/comm"; sleep 1; echo -e '\f'; done | yad --no- 
buttons --no-focus --geometry 250x10 --fixed --text-info -- 
title="Active window" --listen

Answer 5

If you are using gnome then can use the following solution.

Full Disclosure: The github link bellow is my project.

Please look at https://github.com/blueray453/gnome-utils-by-blueray453/blob/main/appFunctions.js

GetAppFromFocusedWindow() {
    let w = global.get_window_actors().find(w => w.meta_window.has_focus() == true);

    let tracker = Shell.WindowTracker.get_default();
    let app = tracker.get_window_app(w.meta_window);
    return app.get_id();
}

You need gnome extension to access data about windows and shell. You see the global. and Shell.WindowTracker, you can not import these is gjs or python.

Please check Could not find Meta, Shell & St in Python's GTK bindings which gnome extension documentaion has.

If you install this extension then the command you would run is:

dbus-send --print-reply=literal --session --dest=org.gnome.Shell /org/gnome/Shell/Extensions/GnomeUtilsApps org.gnome.Shell.Extensions.GnomeUtilsApps.GetAppFromFocusedWindow

You can bind this command to a key.