The psacct package contains several utilities for monitoring process activities, including ac, lastcomm, accton and sa. The ac command displays statistics about how long users have been logged on. The lastcomm command displays information about previous executed commands. The accton command turns process accounting on or off. The sa command summarizes information about previously executed commmands. Install the psacct package if you’d like to use its utilities for monitoring process activities on your CentOS 5.4 system.
Installing the psacct package
Use yum command if you are using CentOS 5.4 / Fedora 11 / RHEL 5.4:
# yum install psacct
