Chapter 11. System Maintenance

11. System Maintenance

IN THIS CHAPTER

System Administrator and Superuser	427
System Maintenance Tools	430
sudo: Performs Specific Tasks as Another User	431
System Operation	435
Booting the System	436
Important Standard Directories and Files	444
lookupd: Which Service to Look at First	455
The Superserver	456
DHCP	464
PAM	466
fink: Downloads and Installs Software	470

The job of a system administrator, or maintainer, is to keep one or more systems useful and convenient for users. On a Mac OS X system, the administrator and user may both be you, with you and a single computer only a few feet apart. Alternatively, the system administrator may be halfway around the world, supporting a network of systems, with you simply one of thousands of users. A system administrator can be one person who works part-time taking care of a system and perhaps is also a user of the system. Alternatively, the administrator can be several people, all working full-time to keep many systems running.

A well-maintained system

• Runs quickly enough that users do not get too frustrated waiting for the system to respond or complete a task.

• Has enough storage to accommodate users' reasonable needs.

• Provides a working environment appropriate to each user's abilities and requirements.

• Is protected from malicious and accidental acts that might potentially alter its performance or compromise the security of the data it holds and exchanges with other systems.

• Is backed up regularly with recently backed-up files readily available to users.

• Has recent copies of the software that users need to get their jobs done.

• Is easier to administer than a poorly maintained system.

In addition, a system administrator should be available to help users with all types of system-related problems, from logging in to obtaining and installing software updates to tracking down and fixing obscure network issues.

Much of the material in this chapter applies equally to Mac OS X versions 10.3 and later, and to both Mac OS X and Mac OS X Server. Where information is specific to a particular version or release, it is so marked.

Because so many services exist, along with different ways to configure or use them, this chapter cannot discuss every system configuration or every action you will have to take as a system maintainer. Instead, it familiarizes you with the concepts you need to understand and the tools you need to use to maintain a Mac OS X system. Where it is not possible to go into depth about a subject, the chapter provides references to other sources.

This chapter assumes that you are familiar with the following terms. Refer to the Glossary (page 919) for their definitions.

block (device)	environment	mount (a device)	spawn
daemon	filesystem	process	system console
device	fork	root filesystem	X server
device filename	kernel	runlevel
disk partition	login shell	signal