# 9 Set up cron

Several Mailman features occur on a regular schedule, so you must set up cron to run the right programs at the right time6.

If your version of crontab supports the -u option, you must be root to do this next step. Add $prefix/cron/crontab.in as a crontab entry by executing these commands:

        % cd $prefix/cron
        % crontab -u mailman crontab.in

If you used the --with-username option, use that user name instead of `mailman` for the -u argument value. If your crontab does not support the -u option, try these commands:

        % cd $prefix/cron
        % su - mailman
        % crontab crontab.in

#### Footnotes

... time 6
  Note that if you're upgrading from a previous version of Mailman, you'll want to install the new crontab, but be careful if you're running multiple Mailman installations on your site! Changing the crontab could mess with other parallel Mailman installations.