IRIX Advanced Site and Server Administration Guide

Chapter 1
System Administration Basics

The system administrator is responsible for all tasks that are beyond the scope of end users, whether for system security or other reasons. The system administrator will undoubtedly use the more advanced programs described in this guide.

A system administrator has many varied responsibilities. They can be organized into the following categories:

Operations - seeing that the machine stays up and running, scheduling preventive maintenance downtime, adding new users, installing new software, and updating the /etc/motd and /etc/issue files. See Chapter 2, "Operating the System." Also see Chapter 3, "User Services."



Failure Analysis - troubleshooting by reading system logs and drawing on past experience. See "Operating Policies". Also see "System and Site Policies".



Capacity Planning - knowing the general level of system use and planning for additional resources when necessary. See Chapter 7, "Disks and Tape Drives" and Chapter 5, "Tuning System Performance."



System Tuning - tuning the kernel and user process priorities for optimum performance. See Chapter 5, "Tuning System Performance" and Appendix A, "IRIX Kernel Tunable Parameters."



Resource Management - planning process and disk accounting and other resource sharing. See Chapter 14, "System Accounting" and "Disk Use and Quotas".



Networking - interconnecting machines, modems, and printers. See Chapter 15, "Understanding Silicon Graphics' Networking Products."



Security - maintaining sufficient security against break-ins as well as maintaining internal privacy and system integrity. See Chapter 12, "System Security."



User Migration - helping users work on all workstations at a site. See Chapter 15, "Understanding Silicon Graphics' Networking Products."



User Education - helping users develop good habits and instructing them in the use of the system. See Chapter 3, "User Services."



Backups - creating and maintaining system backups. See Chapter 6, "Backing Up and Restoring Files."

Superuser Account

Most system administration is performed while the system administrator is logged in as root (the superuser). This account is different from an ordinary user account because root has access to all system files and is not constrained by the usual system of permissions that controls access to files, directories, and programs. The root account exists so that the administrator can perform all necessary tasks on the system while maintaining the privacy of user files and the sanctity of system files. Other operating systems that do not differentiate between users have little or no means of providing for the privacy of users' files or for keeping system files uncorrupted. UNIX systems place the power to override system permissions and to change system files only with the root account.

All administrators at your site should have regular user accounts for their ordinary user tasks. The root account should be used only for necessary system administration tasks.

Administration Tools

Depending on the exact configuration of your system, you may have the following tools available for performing system administration:

System Manager

This tool, available on graphics workstations, provides easy access to system administration functions. It features a quick and easy method of performing most system administration tasks. The System Manager is available only on those systems that have graphics capability.

Command-line tools

The IRIX system provides a rich set of system administration tools that have command-line interfaces. These are especially useful for automatically configuring systems with shell scripts and for repairing the system in unusual circumstances, such as when you must log in remotely from another system.

For example, using command-line tools, a site administrator can alter the system automatically at designated times in the future (for instance, to distribute configuration files at regular intervals). These commands are available on all IRIX systems.

The IRIX Reference Pages

IRIX reference pages, also known as man pages, describe commands, subroutines, and other elements that make up the IRIX operating system. This collection of entries is one of the most important references for a site administrator.

The reference pages are available online. To view a reference page, use the man command at the shell prompt. For example, to see the reference page for diff, enter:

man diff 

It is a good practice to print those reference pages you consistently use for reference and those you are likely to need before major administrative operations and keep them in a notebook of some kind.

Each command, system file, or other system object is described on a separate page. The reference pages are divided into seven sections, as shown in Table 1-1. When referring to reference pages, this document follows a standard UNIX convention: the name of the command is followed by its section number in parentheses. For example, cc(1) refers to the cc reference page in Section 1.

Table 1-1 shows the reference page sections and the types of reference pages that they contain.

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