Quick-and-dirty way to ensure only one instance of a shell script is running at a time

Question

What\'s a quick-and-dirty way to make sure that only one instance of a shell script is running at a given time?

Answer 1

Really quick and really dirty? This one-liner on the top of your script will work:

[[ $(pgrep -c "`basename \"$0\"`") -gt 1 ]] && exit

Of course, just make sure that your script name is unique. :)