why won't my cron command work?

Question

I have manually added a command to my crontab file (Monterey 12.6.9). Pretty simple; the crontab entry is something like:

0 10 * * * mv /Users/me/Desktop/test /Users/me/Desktop/test2

Which means, at 10am every day, do this rename.

But it simply doesn't work. Other commands in my crontab file work fine, which suggests that cron IS actually executing. I HAVE given the cron app "Full Disk Access" in Security & Privacy. That mv command works fine as a terminal command. Not sure where the cron log is, so I haven't pieced together what is happening. This is confusing. Advice?

Answer 1

This works on my Ventura system, and it should work on your Monterey system...

I don't think cron has a "log file" per se, and so I'll suggest you get into the habit of creating and using a file to capture the output of stdout and stderr from all cron jobs. It's the best way to troubleshoot mysterious cron issues.

FROM:

0 10 * * * mv /Users/me/Desktop/test /Users/me/Desktop/test2

TO:

0 10 * * * mv /Users/me/Desktop/test /Users/me/Desktop/test2 >> /Users/me/Desktop/test_log 2>&1

The information in the file test_log should contain something useful, and suggest where the issue is. I suspect - in this case - it's something simple.

Here's the breakdown on the addition:

• >> a redirect (with augmentation instead of replacement)

• 2>&1 redirect stderr to stdout; effectively combines both streams into a single stream

Another good habit with crontab entries that name an executable file is to specify the full path to that executable. You'll get away with it when the executable is in the PATH, but it may not be obvious what cron's PATH actually is.

Yet another good habit with cron is to turn OFF the default MAILTO feature. This is done by adding this line at or near the top of your crontab:

MAILTO=""