How do I make sure my bash script isn't already running?

Question

I have a bash script I want to run every 5 minutes from cron... but there\'s a chance the previous run of the script isn\'t done yet... in this case, i want the new run to j

Answer 1

In some cases, you might want to be able to distinguish between who is running the script and allow some concurrency but not all. In that case, you can use per-user, per-tty or cron-specific locks.

You can use environment variables such as $USER or the output of a program such as tty to create the filename. For cron, you can set a variable in the crontab file and test for it in your script.