Introduction

The commands in this section are all used to tell the system to do something at (or until) a later time.

Proper use of these commands is the key to an efficiently run system. Throughout this book I have made suggestions about tasks that should be automated and run on a regular basis. These include, but are not limited to the following:

system security checks (passwords, file access )

cleanup of temporary files (rm /tmp/*)

updating system databases (updatedb)

backups and archiving (tar, shar)

The following commands are included in this section:

`at`	Add a job to the scheduling queue.
`atq`	Display the contents of the scheduling queue.
`atrm`	Remove a job from the scheduling queue.
`batch`	Execute queue only when system resources permit.
`crontab`	Maintain schedule of jobs to be executed.
`sleep`	Wait some number of seconds.
`usleep`	Wait some number of microseconds.