Cron is used as the de-facto job scheduler for Unix.
Cron stands for “chronograph”.
Every user can specify scripts or programs to run at specific time intervals in a text file called “crontab”.
Access/edit crontab file:
* * * * * command to execute|-->Day of week (0:Sunday to 7)
|@reboot||Run once at starttup||-|
|@yearly||Run once a year||0 0 1 1 *|
|@annually||Same as @yearly||0 0 1 1 *|
|@monthly||Run once a month||0 0 1 * *|
|@weekly||Run once a week||0 0 * * 0|
|@daily||Run once a day||0 0 * * *|
|@midnight||Same as @daily||0 0 * * *|
|@hourly||Run once every hour||0 * * * *|