Kill all detached processes-CodePudding

I have a script that gets a wallpaper from Unsplash, then sets it. I setup a flag --repeat to continuously get images based on a specified interval. The script functions perfectly but to make this happen I used & disown to detach the process so it stays running in the background

My issue is trying to kill the old process(es) when I run the script again. I used to use kill $(ps -ef | awk '/script_name/{print $2}') to kill the existing processes. Of course doing this, I can't recommend anyone else use the script.

while read line ; do
    case $line in
        *-r*) [[ $line =~ $$ ]] || kill `echo $line | cut -d' ' -f2` ;;
    esac
done < <(ps -ef | grep -w 'bg.sh')

I was using this at the top of said script but as of today the processes that spawn aren't named by the script's name, so now I can't figure out a way to find them, let alone kill them; Of course causing above snippets to stop working. I've tried just running kill $! at the top of the script but I must be doing something wrong. All the sources I find online have only confused me more

CodePudding user response：

If you want to kill all already running instances of a certain script, you can add something like this at the top of script;

for pid in $(pidof -x SCRIPT_NAME); do
    if [ "$pid" != $$ ]; then
        kill "$pid"
    fi
done

You can also try using killall instead of kill.

killall SCRIPT_NAME

CodePudding user response：

You could store the process id in a .pid file. When starting the new script, you can let it read that file and kill the old script.

Example:

#!/bin/bash

PIDFILE=/fixed/path/to/script.pid

if [[ -e $PIDFILE ]]; then               # check if the .pid file exists
    OLDPID=$(<"$PIDFILE"))               # read it
    while kill "$OLDPID" 2>/dev/null     # try to kill it
    do
        sleep 1                          # sleep a little
    done
    echo "$OLDPID is dead"
fi

# Store the new pid
trap 'rm "$PIDFILE"' EXIT
echo $$ > "$PIDFILE"

# let the script do what it's supposed to do here

You could add a limit to how many times it should try to kill the old script too and do a kill -0 "$OLDPID" afterwards just to confirm that it's actually dead.