Linux Server and Workstation Configuration How To

Files

• “username” user’s cron file location

  /var/spool/cron/{username}

• Root's crontab file

  /var/spool/cron/root

• Configuration file for cron,

  /etc/crontab

Cron service

Valid values for cron job

• Minutes - from 0 to 59
• Hours - from 0 to 23
• Day of month - from 1 to 31
• Month - from 1 to 12 (also from jan to dec)
• Day of week - from 0 to 6 (0 is sunday, also from sun to sat)

Cron monitoring commands

• Check cron config

  # chkconfig --list | grep crond
# ps -ef | grep cron

• Show current cron jobs of user

  # crontab -l

• Show current cron jobs of user root

  # crontab -u root -l

• Delete cur cron jobs

  # crontab -r

• Delete user's cur cron jobs

  # crontab -u root -r

• Edit the cron tab jobs

  # crontab -e

• Edit the user's cron tab jobs

  # crontab -u root -e

• Install cron job for user root from file /var/spool/cron/root content

  # crontab -i -u root /var/spool/cron/root

Example of cron file