cron Daemon I: Scheduling Processes

cron Daemon I: Scheduling Processes 


Scheduling Processes 

Using the cron Daemon 

The at daemon is great; however, it has one key drawback. It can only schedule a job to run once
in the future. That’s not a problem if you only want the job to run once. However, there will be
many times when you want a job to run in the future on a regular schedule. For example, you may
need to run a process, such as a backup utility, every day at a certain time. In this situation, the at
daemon doesn’t cut it. You need a tool that can handle repetitious schedules.



The cron daemon can do just that. Unlike at, cron can run commands on a schedule you
specify. It’s a very powerful, very useful service. I use at occasionally. However, cron is a service
hat I use all of the time. In fact, I would have a hard time getting my work done without it.
Most of my clients’ offices are many miles from my office. Making rounds just to run backups
for all of my clients each day would take up all my time. Of course, I don’t dare trust my clients’
administrative personnel to make sure backups occur each day. Instead, I set up the cron daemon
to run the backups for me. That way, I know that backups are occurring on a regular schedule
and that the correct command has been issued to create them.
In this part of the chapter, we’ll discuss the following:



• How cron works
• Using cron to manage scheduled system jobs
• Using cron to manage scheduled user jobs







LX0-104 Exam Objectives (L)