This is exactly how you do it. Setting up a cron job to run every 30 minutes can be done like this: crontab -e and put this line in there 0,30 * * * * your_comm

This is exactly how you do it. Setting up a cron job to run every 30 minutes can be done like this: crontab -e and put this line in there 0,30 * * * * your_command or like 0/30 * * * * your_command. The second one works for me, I am on a mac. Make sure the user who runs the job has permission to overwrite the file.