27.2. At and Batch

While Cron is used to schedule recurring tasks, the At utility is used to schedule a one-time task at a specific time and the Batch utility is used to schedule a one-time task to be executed when the system load average drops below 0.8.

27.2.1. Installing At and Batch

To determine if the at package is already installed on your system, issue the rpm -q at command. The command returns the full name of the at package if already installed or notifies you that the package is not available.
To install the packages, use the yum command in the following form:
 yum  install  package 
To install At and Batch, type the following at a shell prompt:
~]# yum install at
Note that you must have superuser privileges (that is, you must be logged in as root) to run this command. For more information on how to install new packages in Red Hat Enterprise Linux, see Section 8.2.4, “Installing Packages”.