CHAPTER 12cron
The system scheduler on UNIX and Linux systems is called cron
. Its purpose is to run commands, series of commands, or scripts on a predetermined schedule. Normally these tasks are performed on systems that run 24 hours a day, 7 days a week. Writing cron
scripts to perform system maintenance, backups, monitors, or any other job that you would want to run on a schedule is a very common task. There are a few subtleties with cron
however, that many users and administrators may be unaware of.
crontab Entries
On a UNIX or Linux system, the cron
daemon process runs all the time. A daemon is generally a program that runs as a background task and provides some type of service, in this case a scheduler. A run control (rc
) script starts ...
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