It is very important to know what are the activities for applications and users in linux operating system. This will very useful in later time or in case of problems. For this purpose, i would recommend psacct or acct tools to be install. psacct or acct is a free monitoring program to monitor users and applications activity on linux server. This program will display how long user accessing the server, what command are they issuing, how many processes and display logs for commands. psacct and acct are similar tool, psacct is for RPM based linux but acct is for Debian based.
1. If you are runninng Linux CentOS or Redhat, you should use the following command to install pssacct :