Handling Foreground and Background Scripts

Handling background scripts and foreground scripts became necessary part of scripting in linux. For examples,

• how to avoid running a background script if the script is already running background? Can a script test itself it is already running?

• how to avoid executing a script residing in $PATH from dmenu, bemenu or any other equivalent, if the script is written to run in terminal interactively or foreground?

To avoid running a background script that is already running, put the following at the top of the script.

SCRIPTNAME=$(basename -- "$0")

if pidof -x "$SCRIPTNAME" -o $$ >> /dev/null 2>&1; then

    notify-send -t 9000 "Already Running" "The script is already running. So, clean exit."

    exit 0

fi

.....

To avoid executing a script residing in $PATH from dmenu, bemenu or any other equivalent if the script is written to run in terminal interactively or foreground, put the following at the top of the script.

case $(ps -o stat= -p $$) in

    *+*)

        echo "continue..."

        ;;

    *)

        notify-send -t 2700 "clean exit" "the script is to be run only in terminal."

        exit 0

        ;;

esac

.....