cron script to keep an app running

persist.sh

#!/usr/bin/env bash

PIDFILE="/mnt/tmp/myapp.pid"

if [ -e "${PIDFILE}" ] && (ps -u $(whoami) -opid= |
                           grep -P "^\s*$(cat ${PIDFILE})$" &> /dev/null); then
  echo "Already running"
  exit 99
fi

pushd /path/to/myapp/ > /dev/null 2>&1
myapp -a args >/dev/null 2>&1 &

echo $! > "${PIDFILE}"
chmod 644 "${PIDFILE}"