4.5. Summary

System services are those programs that run behind the scenes on any Linux system. Many system services are network server programs, but others are purely local in action. Knowing how to start and stop system services, both on a temporary and a permanent basis, will give you control over how your computer behaves—what network servers it provides to the world, what local utilities it runs, and so on. Most system services are run via SysV startup scripts or via a super server, but you may also use local startup scripts to do the job.

Because system services don't attach themselves to a console, they don't normally display messages for you on your screen. Instead, they write messages to log files. These messages can include warnings about security violations, complaints about unexpected events, and more routine data about normal operations. Knowing how to examine and search log files will enable you to keep an eye on your system's operation, both to verify normal functioning and to investigate problems—with any luck before they become serious!