Crontab ------- less /etc/crontab #tells when the cron.x's run a crontab entry is structured as follows: 0 0 1 * * root logrotate /etc/logrotate.conf You can use the divide-by operator like */2 to indicate every minute (*) divided by 2, thus... every other minute. * */2 * * * /foo/bar # would indicate every other hour * */6 * * * /foo/bar # would indicate every 6 hours OR * 0,6,12,18 * * * /foo/bar # would indicate every 6 hours with hour specified * * */2 * * /foo/bar # would indicate every other day 0 21 * * * /foo/bar # would indicate every day at 9pm 0 21 * * 1-5 /foo/bar # would indicate every day M-F at 9pm OR 0 21 * * Mon-Fri /foo/bar # same as above / is the separator between moment and repeat factor For more examples: man 5 crontab