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A tool for checking system crontab files (/etc/crontab and /etc/cron.d normally) for errors and common mistakes.
Python Shell
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Crontab linter

chkcrontab is a script to check crontab files like those in /etc/cron.d and /etc/crontab. It tries to catch glaring errors and warn on suspect lines in a crontab file. Some valid lines will generate warnings. Certain silly yet valid crontab lines will generate errors as well.

Run this by doing:

chkcrontab crontab_file

Errors will cause a non-zero exit code. Warnings alone will not.

To see sample output for a bad crontab, run the following:

./chkcrontab ./tests/test_crontab

See the ./tests/test_crontab.disable crontab for how to disable warnings and errors.


Contributions are welcome! Please add unit tests for new features or bug fixes. To run all the unit tests run ./setup test. If you have tox installed, just run tox.

You can review coverage of added tests by running coverage run test and then running coverage report -m.

Note that tests are run on Travis for all supported python versions whenever the tree on github is pushed to.

The main site for this is on with a backup site at github. Use whichever is convenient, the maintainer will push accepted patches to both.


  • Look for duplicate entries. Puppet sometimes loads up crontabs with dups.
  • Check for backticks. (why?)
  • Make sure MAILTO and PATH are set (perhaps others?).
  • Add tests for command line.


  • Kevin Lyda: Who got burned one too many times by broken crontabs.
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