Automation with Cron

Cron Jobs

 
# Edit user's crontab
crontab -e                # Edit crontab
crontab -l                # List cron jobs
crontab -r                # Remove all cron jobs
 
# System cron directories
/etc/cron.hourly/
/etc/cron.daily/
/etc/cron.weekly/
/etc/cron.monthly/
 

Crontab Format

 
* * * * * command_to_execute
│ │ │ │ │
│ │ │ │ └─ Day of week (0-7, Sunday=0/7)
│ │ │ └─── Month (1-12)
│ │ └───── Day of month (1-31)
│ └─────── Hour (0-23)
└───────── Minute (0-59)
 

Examples:

 
# Run every minute
* * * * * /path/to/script.sh
 
# Run at 2:30 AM daily
30 2 * * * /path/to/script.sh
 
# Run every Monday at 5 PM
0 17 * * 1 /path/to/script.sh
 
# Run every 10 minutes
*/10 * * * * /path/to/script.sh