The crontab file :::: The cron application launches automatically at system startup and runs continuously in the background executing commands as instructed by the crontab files. These files tell cron exactly what commands to run and when to run them. In fact, each user account can have its own crontab file. The system crontab found in /private/etc belongs to the super-user, or root account, and therefore can specify commands requiring the same total system access allowed to root.