Cron in Linux

• Check Cron whether installed in linux: rpm -qa | grep cron
• Start cron service in RHEL, service crond start
• Edit tasks: crontab -e, the task configure structure is
  [Minute] [Hour] [Day of the month] [Month of the year] [Day of the week] [command]
  "*" represent any number. "/" means every. "-" means to. "," separate more than one value eg: */2 2-4 2,5,7 * * means every 2 mins between 2 o'clock and 4 o'clock in the second, fifth and seventh day in each month.
• Del tasks: crontab -r
• List tasks: crontab -l