Guide to Linux Installation and Administration, 2e1 Chapter 7 The Role of the System Administrator

Guide to Linux Installation and Administration, 2e 1

Chapter 7

The Role of the System Administrator

Guide to Linux Installation and Administration, 2e 2

Objectives

In this chapter, you will:

• Explain the role of a system administrator

• Discuss the responsibilities of a system administrator

• Use basic system administration commands in Linux

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Working as a System Administrator

• The role of a Linux system administrator is to keep Linux-based computer systems running efficiently

• A system administrator works as part of the Information Systems (IS) or Information Technology (IT) department of an organization

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Working as a System Administrator

• The IS or IT departments work in two areas:– Internal information systems– Organizational information viewed by the public

over the Internet• The help desk team directly solves problems for

end users

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The Position of a System Administrator within Small Company

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The Position of a System Administrator within Large Company

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Tasks of a System Administrator

• System administrators perform the following tasks:– Help users solve problems

– Train users

– Inform management of technical developments

– Maintain system hardware

– Create new user accounts

– Define procedures and policies

– Plan systems

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Ethics and the System Administrator

• System administrators are trusted employees• System administrators have access to valuable

personal and business data• Legal and ethical rules control work of a system

administrator

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Principles of Maintaininga Linux System

• Linux utilities are programs used for system administration

• Linux system is designed to be used by multiple users

• Each program or system service relies on a separate plain-text configuration file

• Most Linux command-line utilities are designed to do one task very well

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Linux Configuration Files

• Program and system services create and maintain its own configuration information

• The configuration files for programs managed by the system administrator are stored in the /etc directory

• Configuration files for programs that are used by only a single user are stored in that user’s home directory

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Some Configuration Files Used by Linux

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Advantages of Multiple Plain-Text Configuration Files

• Using plain-text configuration files has several advantages:– Allow complex configurations

– Permit modifications using any text editor

– Easy to write a program to manipulate the configuration

– Each file is small and independent

– Flexibility

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Advantages of Multiple Plain-Text Configuration Files

• Other utilities designed to provide a framework for configuring all Linux programs:– KDE

– Gnome

– Webmin

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Configuring a Program with a Graphical Utility

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The KDE Control Center

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A Gnome Configuration Utility

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Understanding Files, Devices, and Processes

• A device is a hardware peripheral• Devices are accessed via the /dev directory,

either directly or by creating an association with another system resource

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Understanding Files, Devices, and Processes

• Processes are the programs running on Linux• Program is a piece of software that executes on

the Linux system• A daemon is a background process• A thread is a part of a process, or subprocess

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Daemons Running on Linux

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Multiple Users, Multiple Processes

• Linux supports multiple users working at the same time

• Each user account can execute multiple programs, and each of these processes is associated with the user that started it

• System administrator can log in as root to manage all processes on the system

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Using Small, Efficient Utilities

• To provide flexibility, Linux commands have numerous options

• All command options are focused on a single type of task

• Each option is represented by:– a hyphen followed by a single letter

– two hyphens followed by a word describing the option

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Common Options of the ls Command Options

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Combining Command Options

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Standard Input and Output

• Channels of communication in Linux can be redirected

• The standard input channel (STDN) data provided by the kernel comes from the keyboard

• A program sends data to the standard output channel (STDOUT) to display that information on-screen

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Standard Input and Output

• Error messages are written to standard error (STDERR)

• A pipe connects the output channel of one command to the input channel

• Pipes are used to connect the output of one application to the input of another application

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Creating a Pipe between Two Applications

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Redirecting Input and Output

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Using Basic Administration Tools

• A system administrator should know about a number of basic Linux utilities and the options supported by those utilities

• A single utility has a simple function• Multiple utilities can be combined together using

redirection

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Case Sensitivity in Linux

• Everything in Linux is case sensitive• Program names and commands in Linux are all

lowercase

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Filenames and File Extensions

• File extensions can be used for convenience in Linux, but they are not important

• Filenames in Linux can be up to 256 characters, include most special characters except a forward slash

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Learning about Linux Commands

• To learn about Linux commands:– Use a command’s -- help option

– View the online manual pages

– Use the info command

• The apropos command can help you locate an appropriate command based on a keyword search of man pages

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Using Regular Expressions

• A regular expression provides a flexible way to encode many types of complex patterns

• Regular expression can be used as parameters to Linux commands

• Regular expressions operate in the same way as wildcards

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Common Regular Expressions in Linux

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Example Regular Expressions

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Deleting Files in Linux

• Deleting files using the rm command in Linux is permanent

• After using rm, deleted files cannot be recovered

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Deleting Files in Linux

• To protect users from accidentally erasing files:– Use the safedelete utility

– Use the rm command with the –i option, which prompts you for confirmation before deleting a file

– Use the trashcan on the KDE or Gnome Desktop

– Use a low-level disk editing tool

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Finding What You Need

• The locate and find commands help you locate files within Linux

• The locate command is used to search an index of all files on your Linux system

• The find command lets you specify properties of the file to match

• The grep command searches within text files for patterns that you specify using regular expressions

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Reviewing System Processes

• Process ID (PID) is a unique number identifying a process

• The ps command provides a PID and other information about each process running on Linux

• The kill command is used to end a process

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Summary

• The role of a Linux system administrator is to keep Linux-based computer systems running efficiently

• System administrators maintain end-user systems, Internet systems, train and support users, and solve system problems

• Each program and service in Linux is configured using plain-text configuration files

• Graphical configuration utilities are used for system administration

• A single task performed by a process cab be split into multiple threads, or subtasks

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Summary

• Linux supports multiple users working at the same time

• Communications to and from program is provided by standardized channels STDN, STDOUT, and STDERR

• To learn about Linux commands, review the online documentation and view command’s options

• Regular expressions provide a flexible way to encode many types of complex patterns

• Linux provides the locate, find, and grep tools to help you locate specific files and search within files