Bash regularly restart a program

restarter.sh

#!/bin/bash

set -euo pipefail

if [ $# -lt 2 ]; then
  echo "Usage: $0 SCHEDULE PROG [ARGS]..." >&2
  echo "SCHEDULE is used in 'date -d <SCHEDULE>'." >&2
  echo "Example: $0 '1 hour' myprog --arg" >&2
  exit 1
fi


function stop_prog() {
  if [ -n "${prog_pid:-}" ]; then
    echo -n "Stopping PID $prog_pid... " >&2
    kill $prog_pid
    wait $prog_pid
    echo "done" >&2
  fi
}

trap "echo Received exit signal >&2 && stop_prog" EXIT

restart_schedule="$1"
shift

while true; do
  # Start program in background
  "$@" &
  prog_pid=$!

  # Wait for next restart
  next_restart="$(date -d "$restart_schedule")"
  next_restart_unix="$(date -d "$next_restart" "+%s")"
  echo "Started $1 as PID $prog_pid. Next restart: $next_restart" >&2
  while true; do
    sleep 10
    if [ "$(date "+%s")" -gt $next_restart_unix ]; then
      stop_prog
      break
    fi
  done
done