VAEVICTIS OS

Learn / Crontab builder

Crontab builder

Cron runs a command for you at fixed times: a backup every night, a clean-up every Monday. A schedule is five fields. Build one here, or paste one you found and read what it really does.

EXAMPLES
LINE FOR YOUR CRONTAB

    

    
The fields. Minute 0-59, hour 0-23, day of the month 1-31, month 1-12, weekday 0-7 (0 and 7 are Sunday). * means any, */15 every 15, 1-5 a range, 1,15 a list. If you set both a day of the month and a weekday, cron runs on either of them, not only when both match.

    
How to save it.
      
    
        
  1. Open your schedule with crontab -e (the first time it asks for an editor: choose nano).
    2. 
        
  2. Paste the line at the end, then save with Ctrl+O, Enter and exit with Ctrl+X.
    3. 
        
  3. Check it with crontab -l.
    4. 
      

      If the crontab command is missing, install it with sudo apt install cron.

    
Common mistakes. Cron does not load your desktop session: use full paths (/usr/bin/rsync, $HOME/bin/backup.sh), make the script executable, and send the output to a log file as in the example, or errors disappear silently. The times follow the PC’s clock; if the PC is off at that time, the job is simply skipped.

    
Debian also schedules its own maintenance with systemd timers: systemctl list-timers shows them.

    
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