What is Cron?

Q. Can you explain what is Cron? Why I need cron?

A. Cron is UNIX/Linux service or daemon to execute scheduled commands. It is also known as the clock daemon that executes commands at specified dates and times according to instructions in a file.

Generally, crontab uses a daemon, crond, which runs constantly in the background and checks once a minute to see if any of the scheduled jobs need to be executed. If so, it executes them. These jobs are generally referred to as cron jobs.

Cron is controlled by a set of files called "crontabs". There is the master file in /etc/crontab. Each users cronjob is stored in /var/spool/cron/username directory.

Editing Crontab or setting up your own job

Just type following command:
$ crontab -e

See also

• How do I add jobs to cron under Linux or UNIX oses?
• Linux Start and stop the cron or crond service

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