cron

gistfile1.txt

=== Cron

Here's how to create a crontab that runs a rake task every 15 minutes, as the user webapp:

<tt>
sudo crontab -u webapp -e
</tt>

Vim pops up. Add a line to the file as follows:

<tt>
*/15 * * * * cd /u/apps/ods/current && /usr/bin/rake -f /u/apps/ods/current/Rakefile some:rake_task RAILS_ENV=production
</tt>

A little background about all those stars:

*/15 * * * * 'command'
 |   | | | |
 |   | | | -- Weekday (0 - 6, where 0 => Sunday)
 |   | | ---- Month (1 - 12)
 |   | ------ Day (1 - 31)
 |   -------- Hour (0 - 23)
 ------------ Minute of the hour (0 - 59)

Notes:

* Include path to entire command, as crond's environment is minimal
* The */15 syntax indicates "every fifteen minutes, starting at 0", 0 being midnight.
* You may include specific minutes, for instance by doing: 10, 25, 40, 55
* The same applies for days of week, months, days, and hours.

Other (from crontab help):

usage:  crontab [-u user] file
        crontab [-u user] [ -e | -l | -r ]
                (default operation is replace, per 1003.2)
        -e      (edit user's crontab)
        -l      (list user's crontab)
        -r      (delete user's crontab)
        -i      (prompt before deleting user's crontab)