It’s quite usefull when want to run scripts under given date and time. At this moment, you will need Cron (for Unix/Linux) and Lauchd (OSX).
Cron and Crontab
Create Cron Job
$ crontab -e
You can add one line like folliwng:
1 2 3 4 5 /path/to/command.sh arg1 arg2
or
1 2 3 4 5 /root/command.sh
This means to run command.sh with parameter or not.
The Cron job definition
The most sophiscated stuff is the cron expression, like previous “1 2 3 4 5 “ what does it means?
* * * * * 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)
Special String
And there’s special string for simplify configuration:
| Special String | Meaning |
|---|---|
| @reboot | Run once, at startup. |
| @yearly | Run once a year, “0 0 1 1 *”. |
| @annually | (same as @yearly) |
| @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) |
| @hourly | Run once an hour, “0 * * * *”. |
This means, you can wirte like this:
@daily /root/command.sh
List Cron Jobs
$ crontab -l
$ crontab -u username -l
Lauchd and Launchctl
Instead of simple commands, OSX’s alternative tool is really urgly.
| You need to create XML …. -_- |
Whatever, if later have to use it. Here’s a pretty good documentation. Schedule jobs using launchd