Run Shell Scripts on a Schedule

Question

Is there "a right" way to run shell scripts on a schedule in modern versions of MacOS? My usual go to for this has been using the cron command -- but recent changes make seem like this isn't in the front of Apple's mind these days.

Is there a better option than cron for running programs on a schedule in modern (Big Sur era) MacOS? Is my only option biting the bullet and learning how launchd works or is there something simpler/easier that I can use?

Answer 1

If there is a “right” way from Apple’s point of view, then it’s launchd. Not that cron is “wrong” per se but it is not the “preferred” way.

However, as you indicated, launchd can be a pain to work with.

There are two good apps to try:

1. https://www.soma-zone.com/LaunchControl/ ¹

2. https://www.peterborgapps.com/lingon/

Lingon has been around for a long time and is probably better known, but I switched to LaunchControl a few years ago and much prefer it.

The developer also maintains https://launchd.info which is a helpful tutorial website to understand how launchd works.

LaunchControl also has a built-in tool that can mitigate issues around Full Disk Access, making it easier to deal with macOS' restrictions.

---

There is another, simpler option: Keyboard Maestro. Not only does Keyboard Maestro have a feature to run scripts (or macros, etc) at a specific time or recurring every X minutes, but you can also use cron-style syntax if you want.

Given that Keyboard Maestro is the best automation tool for the Mac, and I'd probably sacrifice a finger rather than be forced to use a Mac without it, you can guess that I strongly recommend Keyboard Maestro. It has a free trial (for other 2 weeks or 30 days, I'm not sure, but it's definitely a long time) and is actively maintained.

---

¹ As of this writing, both the LaunchControl website and launchd.info site appear to be down, which I assume is just a temporary glitch. They were working as recently as last night. If it is still down when you read this, you can download a copy of the latest version (which also has a free trial) from my website here:

https://iusethis.luo.ma/launchcontrol/LaunchControl-1.52.3.tbz2

Answer 2

You can still use crontab in the same way as you do it on a linux box — MacOS does not run a real cron service and crontab is just a wrapper that delegates to launchd saving you the need to bother with the launchd XML syntax (see under Running a Job Periodically).

Go ahead and create your cron entries using the familiar syntax by running as your regular user:

crontab -e

NOTE: You can also use sudo crontab -e if your task needs to be run as root. You need to make sure that the root user has access to your script though.

Example entry:

0 8 * * * /usr/local/bin/myscript.sh >> /tmp/myscript_errors.log 2>&1

List existing crontab entries:

crontab -l

When cron jobs generate output MacOS creates local mail entries which could show up as You have new mail notifications when you open a new terminal shell. To disable local mail messages add to the top of your crontab the following line:

MAILTO=""

PS: Depending on the version of your MacOS you might need to allow full disc access to /usr/bin/crontab as described in this answer.