watch-run

#!/bin/bash
set -u

usage(){
    cat <<EOF

    $(basename $0) /path/to/file-to-be-watched [--notify] command [...args]

EOF
}

### Set initial time of file
file=${1:-}
[[ -n $file ]] || { echo "Filename to be watched must be supplied"; usage; exit 2; }
shift

notification_enabled=
if [[ "${1:-}" = "--notify" ]]; then
    notification_enabled=true
    shift
fi
first_notification=true
notify(){
    local pfx=
    [[ "$first_notification" = true ]] || pfx="re"
    notify-send "debug-ls" "$(basename $file) ${pfx}started."
    first_notification=false
}

cmd=${@:-}
[[ -n $cmd ]] || { echo "Command must be supplied"; exit 2; }
LTIME=
CMD_PID=

cleanup(){
    [[ -n $CMD_PID ]] && kill $CMD_PID
}
trap cleanup EXIT

while :; do
   ATIME=`stat -c %Z "$file"`
   if [[ "$ATIME" != "$LTIME" ]]; then
        #echo "RUN COMMAND, $ATIME"
        if [[ -n $CMD_PID ]]; then
            echo "---------------------------------------"
            echo "|             Restarting...           |"
            echo "---------------------------------------"
            kill $CMD_PID
        fi
        [[ "$notification_enabled" = "true" ]] && notify
        $cmd &
        CMD_PID=$!
        LTIME=$ATIME
   fi
   sleep 2
done