The Role of the System Administrator

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Chapter 7

• The Role of the System Administrator

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

3
Working as a System Administrator
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• 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

4
Working as a System Administrator
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• 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

5
The Position of a System Administrator within
Small Company
6
The Position of a System Administrator within
Large Company
7
Tasks of a System Administrator
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• 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

8
Ethics and the System Administrator
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• 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
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• 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
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• 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 users home
  directory

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Some Configuration Files Used by Linux
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Advantages of Multiple Plain-Text Configuration
Files
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• 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
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• Other utilities designed to provide a framework
  for configuring all Linux programs
• KDE
• Gnome
• Webmin

14
Configuring a Program with a Graphical Utility
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The KDE Control Center
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A Gnome Configuration Utility
17
Understanding Files, Devices, and Processes
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• 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
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• 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

19
Daemons Running on Linux
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Multiple Users, Multiple Processes
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• 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
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• 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
24
Standard Input and Output
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• 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
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• 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

26
Creating a Pipe between Two Applications
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Redirecting Input and Output
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Using Basic Administration Tools
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• 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

29
Case Sensitivity in Linux
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• Everything in Linux is case sensitive
• Program names and commands in Linux are all
  lowercase

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Filenames and File Extensions
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• 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
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• To learn about Linux commands
• Use a commands -- 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
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• 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
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• Deleting files using the rm command in Linux is
  permanent
• After using rm, deleted files cannot be recovered

36
Deleting Files in Linux
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• 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
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• 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
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• Process ID (PID) is a unique number identifying a
  process
• The pc 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

40
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 commands 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