Crontab Syntax Reference
Complete crontab syntax reference with interactive testing. Learn cron field ranges, special characters, and common patterns with live examples.
Built by Michael Lip
Frequently Asked Questions
What are the special characters in crontab?
Asterisk (*) matches all values. Comma (,) separates multiple values (1,3,5). Hyphen (-) defines ranges (1-5). Slash (/) defines steps (*/5 means every 5th value).
How do I edit my crontab on Linux?
Run 'crontab -e' to open your user's crontab in the default editor. Each line is a cron expression followed by the command to run. Save and exit to install the new schedule.
What is the difference between crontab and cron?
Cron is the daemon (background process) that runs scheduled tasks. Crontab is the file that lists the tasks and their schedules. 'crontab -e' edits your crontab file, and the cron daemon reads it.
How do I log cron job output?
Append '>> /var/log/myjob.log 2>&1' to your cron command to redirect both stdout and stderr to a log file. Without this, cron typically emails output to the user.
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