How to add jobs to cron under Linux ?
To edit your crontab file, type the following command:
$ crontab -e
Syntax of crontabYour cron job looks like as follows:
1 2 3 4 5 /path/to/command arg1 arg2
Where,
• 1: Minute (0-59)
• 2: Hours (0-23)
• 3: Day (0-31)
• 4: Month (0-12 [12 == December])
• 5: Day of the week(0-7 [7 or 0 == sunday])
• /path/to/command - Script or command name to schedule
Same above five fields structure can be easily remembered with following diagram:
* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)
Example(s)
If you wished to have a script named /root/backup.sh run every day at 3am, my crontab entry would look like as follows:
(a) Install your cronjob:# crontab -e(b)Append following entry:0 3 * * * /root/backup.shRun five minutes after midnight, every day:5 0 * * * /path/to/commandRun at 2:15pm on the first of every month:15 14 1 * * /path/to/commandRun at 10 pm on weekdays: 0 22 * * 1-5 /path/to/command Run 23 minutes after midnigbt, 2am, 4am ..., everyday:23 0-23/2 * * * /path/to/commandRun at 5 after 4 every sunday:5 4 * * sun /path/to/command
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