title: Run cron job only if it isn't already running
body: <p>I'm trying to set up a cron job as a sort of watchdog for a daemon that I've created. If the daemon errors out and fails, I want the cron job to periodically restart it... I'm not sure how possible this is, but I read through a couple of cron tutorials and couldn't find anything that would do what I'm looking for...</p>
  <p>My daemon gets started from a shell script, so I'm really just looking for a way to run a cron job ONLY if the previous run of that job isn't still running.</p>
  <p><a href="https://stackoverflow.com/q/851872/825757">I found this post</a>, which did provide a solution for what I'm trying to do using lock files, not I'm not sure if there is a better way to do it...</p>