Administering computers can be a complicated job. Even in small organizations, there are users and groups to configure, backups to create, databases to maintain, and similar chores. Many administrative jobs are time-consuming exercises. If you run them during the day, they can overwhelm a system that s already trying to keep up with your users.
You could change your hours and run these jobs at night. But what if you re responsible for several facilities? Even Linux administrators deserve a personal life.
To support these tasks , Linux includes the at and cron daemons, which help you automate the tasks that you need to run, any time, on any schedule. While at is a onetime management tool, cron allows you to set up jobs to run on regular schedules.
If you don t have an immediate solution, the first place to start troubleshooting is with the log files. Linux logs ”most of which are located in the /var/log directory ”are a rich source of information on the activity of your system. Different log files can help you monitor security, login activity, daemon status, and more.
As a Linux administrator, you should be familiar with a number of basic commands. The ps , top , and kill commands help you manage processes. You can check current logins with who . The nice and renice commands help you prioritize what s running. The nohup command can also help you run commands even after logging out of your account. This chapter covers the following topics:
Using the cron daemon
Using the at daemon
Troubleshooting with logs
Managing processes and users