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== Overview == | == Overview == | ||
Each user can have their own crontab. This allows users to schedule jobs to run at specific intervals. | Each user can have their own crontab. This allows users to schedule jobs to run at specific intervals. | ||
| + | |||
| + | === Example === | ||
| + | 0 */2 * * * /home/username/test.sh | ||
| + | |||
| + | |||
| + | * * * * * command to be executed | ||
| + | ┬ ┬ ┬ ┬ ┬ | ||
| + | │ │ │ │ │ | ||
| + | │ │ │ │ │ | ||
| + | │ │ │ │ └───── day of week (0 - 7) (0 or 7 are Sunday, or use names) | ||
| + | │ │ │ └─────── month (1 - 12) | ||
| + | │ │ └───────── day of month (1 - 31) | ||
| + | │ └─────────── hour (0 - 23) | ||
| + | └───────────── min (0 - 59) | ||
| + | |||
| + | |||
| + | ===Predefined scheduling definitions=== | ||
| + | There are several special predefined values which can be used to substitute the CRON expression. | ||
| + | |||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | !Entry !!Description !!Equivalent To | ||
| + | |- | ||
| + | |<code>@yearly (or @annually)</code> ||Run once a year at midnight in the morning of January 1 ||<code>0 0 1 1 *</code> | ||
| + | |- | ||
| + | |<code>@monthly</code> ||Run once a month at midnight in the morning of the first of the month ||<code>0 0 1 * * </code> | ||
| + | |- | ||
| + | |<code>@weekly</code> ||Run once a week at midnight in the morning of Sunday ||<code>0 0 * * 0 </code> | ||
| + | |- | ||
| + | |<code>@daily</code> ||Run once a day at midnight ||<code>0 0 * * *</code> | ||
| + | |- | ||
| + | |<code>@hourly</code> ||Run once an hour at the beginning of the hour ||<code>0 * * * *</code> | ||
| + | |- | ||
| + | |<code>@reboot</code> ||Run at startup ||<code>@reboot</code> | ||
| + | |} | ||
=== View Job List === | === View Job List === | ||
crontab -l | crontab -l | ||
| + | |||
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| − | [[Category: | + | [[Category:cron]] |
Latest revision as of 17:44, 14 January 2013
Contents
Overview
Each user can have their own crontab. This allows users to schedule jobs to run at specific intervals.
Example
0 */2 * * * /home/username/test.sh
* * * * * command to be executed ┬ ┬ ┬ ┬ ┬ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └───── day of week (0 - 7) (0 or 7 are Sunday, or use names) │ │ │ └─────── month (1 - 12) │ │ └───────── day of month (1 - 31) │ └─────────── hour (0 - 23) └───────────── min (0 - 59)
Predefined scheduling definitions
There are several special predefined values which can be used to substitute the CRON expression.
| Entry | Description | Equivalent To |
|---|---|---|
@yearly (or @annually) |
Run once a year at midnight in the morning of January 1 | 0 0 1 1 *
|
@monthly |
Run once a month at midnight in the morning of the first of the month | 0 0 1 * *
|
@weekly |
Run once a week at midnight in the morning of Sunday | 0 0 * * 0
|
@daily |
Run once a day at midnight | 0 0 * * *
|
@hourly |
Run once an hour at the beginning of the hour | 0 * * * *
|
@reboot |
Run at startup | @reboot
|
View Job List
crontab -l
Add/Edit Job
crontab -e
Reference
http://en.wikipedia.org/wiki/Cron
http://www.freebsd.org/cgi/man.cgi?query=crontab&sektion=1&apropos=0&manpath=FreeBSD+9.0-RELEASE