Hi there,
I just made a little handy script I'm using lately, it is named xfreeze.sh

His function is to pause and resume whatever program running in a X11 window.

Not all games support a pause function when unfocused, and this is not good for power consumption.
In other ones you may want to just stop them for whatever reason (take some time to translate a string -eg: in gta5 when there are subtitles in foreing language while you're driving, cheating... whatever).
I just paused Horizon Chase Turbo to write this post and let my cpu and gpu rest for a while :)

Usage:

  xfreeze.sh Action Target

  Action:
       ask: Ask to pause or continue execution (uses kdialog to ask you what to do)
    switch: Switch execution state paused <-> running

  Target:
    active: Use the active window (pause or resume the active window)
    select: Ask user to click on a window (expects you to click on the window you want to pause)
  _

Dependancies:

• The program to freeze has to be running into an X11 window implementing _NET_WM_PID property
• xprop
• awk
• xdotool (only to use the "select" function)
• kdialog (only to use the "ask" function)

Currenty, i've bound "xfreeze.sh switch active" to a SHIFT+PAUSE hotkey (use whatever tool your de provides to assign custom commands to shortcuts), so that while i'm playing, i hit SHIFT+PAUSE and have my game paused or resumed.

Beware that for how Xorg works, when not using a compositor, when a window is "paused" it does not update his content, so if you minimize the window and restore it while paused, it will be totally black. Also if it is partially obscured by another one, the latter will leave traces on it (win95 effect); resuming the window will make them go away.

Oh, it doesn't work for all the programs, because sometimes their window doesn't implement _NET_WM_PID and I wasn't able to resolve a window id to a pid in those cases, not even xkill is able to work on them, but fortunately they are rare.

Here it is:
 
#!/usr/bin/env bash

# xfreeze.sh [ask|switch] [active|select]

# ask = ask to pause or continue execution
# switch = switch execution state

# active = use the active window
# select = ask user to click on a window


if [ $2 = "active" ] ; then
        PROC=$(xprop -id $(xprop -root | awk '/_NET_ACTIVE_WINDOW\(WINDOW\)/{print $NF}') | awk '/_NET_WM_PID\(CARDINAL\)/{print $NF}')
                else
        PROC=$(xdotool selectwindow getwindowpid)
fi

if [ $1 = "ask" ] ; then
        kdialog --yesno $(</proc/$PROC/comm) --yes-label RESUME --no-label PAUSE
                else
        grep State: /proc/$PROC/status|grep stopped
fi
condition_continue=$?
echo $condition_continue 

if [ $condition_continue = 0 ] ; then 
        echo cont
        kill -CONT $PROC
                else
        echo stop
        kill -STOP $PROC
fi

#cat /proc/$PROC/status #debug

Hope someone will find it useful,
back to Horizon Chase Turbo, cheers!

Last edited by kokoko3k on 22 July 2021 at 4:21 pm UTC