Use in crontabs in front of the real program to hide program output unless there is an error.
A typical crontab entry might look like this:
4 * * * * some-random-job.sh
If some-random-job.sh generates output, you will see it every time the script runs. But if you only want to see the output when the script fails, you can run it through cron-output-hider like this:
4 * * * * cron-output-hider -- some-random-job.sh
Now you'll only get the cron job email when it fails.