MacOS – “cron” processes piling up

activity-monitorcommand linecronmacos

I have cronjobs doing various cleanup tasks:

$ crontab -l
0 * * * * find ${HOME}/Downloads -depth 1 -d -mtime +12h -exec /usr/local/bin/trash {} \;
* * * * * /usr/bin/defaults delete com.apple.Spotlight userHasMovedWindow > /dev/null
* * * * * /usr/bin/defaults delete com.apple.Spotlight windowHeight > /dev/null

However, it seems the jobs, for some reason, never exits. Instead they linger on and show as (cron) companioned by either (find) or (defaults) in the output of ps and in the activity monitor.

It happens for all jobs.

After hours or days, the computer freezes as the OS won't allow any more processes to spawn.

$ sw_vers 
ProductName:    Mac OS X
ProductVersion: 10.15
BuildVersion:   19A583

Best Answer

Redirect stderr to /dev/null as well as stdout:

* * * * * /usr/bin/defaults delete com.apple.Spotlight userHasMovedWindow &> /dev/null
* * * * * /usr/bin/defaults delete com.apple.Spotlight windowHeight &> /dev/null

From trial and error it seems to be the stderr output of those commands that prevents the cronjob from exiting. I have no clue why that is, but it may be related to permissions to mail the output.

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