Chapter 7
The Role of the System
Administrator
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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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
Tasks of a System Administrator
• System administrators perform the following
tasks:
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–
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–
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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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Valued Gateway
Client:
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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Valued Gateway
Client:
Principles of Maintaining
a 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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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 onscreen
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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
Case Sensitivity in Linux
• Everything in Linux is case sensitive
• Program names and commands in Linux are all
lowercase
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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
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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Valued Gateway
Client:
Reviewing System Processes
• 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
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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
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