http://www.perlmonks.org?node_id=11110171


in reply to How many scripts running?

If you only want a single instance of your script running, the easiest approach is to lock the script file itself while the script is running. See Highlander for that approach.

Of course, the locking needs to be done in the top-level invocation, so the best approach is to have a separate top-level script that gets invoked and that locks itself.