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Often, crontab scripts are not executed on schedule or as expected. There are numerous reasons for that:

  1. wrong crontab notation
  2. permissions problem
  3. environment variables

This community wiki aims to aggregate the top reasons for crontab scripts not being executed as expected. Write each reason in a separate answer.

Please include one reason per answer - details about why it's not executed - and fix(es) for that one reason.

Please write only cron-specific issues, e.g. commands that execute as expected from the shell but execute erroneously by cron.

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31 Answers 31

I once was working on a shared server with lots of restrictions.

All the answers here (PATH, SHELL, bash -c,...) could not get my script to work in the crontab.

It did work perfectly when I put the command in a little script file with the PATH, SHELL, and shebang rather than in the crontab itself. I did have to change the permissions to 700.

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