The cron format has five time and date fields separated by at least one blank. There can be no blank within a field value. Scheduled tasks are executed when the minute, hour, and month of year fields match the current time and date, and at least one of the two day fields (day of month, or day of week) match the current date. Leave * * * * * in order to restart failed builds every minute. You can find more information about the cron format here . If you want to check the validity of a cron tab here is a very useful site to do that.