Cron is a time-based job scheduler in Unix-like computer operating systems. People who set up and maintain software environments, use cron to schedule jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. It typically automates system maintenance or administration - though its general-purpose nature makes it useful for things like connecting to the Internet and downloading email at regular intervals. Cron is most suitable for scheduling repetitive tasks. Scheduling one-time tasks is often more easily accomplished using the associated at utility.