Chapter 9

Question 1

Using a semicolon allows you to do what?

command ; command

Answer 1

Combine two commands into one line

known as the list operator

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Question 2

subshell

Answer 2

a child process that is created by either the shell or a shell script when a process is initiated

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Question 3

Variable

DISPLAY

Answer 3

identifies the display. Usually set to :0.0, which indicates the first display on the current computer. If running multiple sessions the counter increases to ID it. :0.0 is the first one, :1.0 is the second, etc

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Question 4

Variable

EDITOR

Answer 4

Some programs launch the program pointed to by the environment variable when they need to call a text editor for you to use.

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Question 5

Variable

HISTSIZE

Answer 5

This variable determines the number of commands that will be saved in your history file

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Question 6

Variable

HOME

Answer 6

Points to your home directory. Some programs use it to help them look for configuration files or as a default locations in which to store files

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Question 7

Variable

HOSTNAME

Answer 7

This is the current TCP/IP hostname of the computer

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Question 8

Variable

LANG

Answer 8

The system holds your current language, specified locale, using this.

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Question 9

Variable

LD_LIBRARY_PATH

Answer 9

A few programs use this environment variable to indicate directories in which library files may be found. It works much like a path

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Question 10

Variable

LOGNAME

Answer 10

This variable holds your username when you are logged into the systems

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Question 11

Variable

MAIL

Answer 11

This variable holds the location of the user’s mail spool. It’s usually /var/spool/mail/username

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Question 12

Variable

PAGER

Answer 12

If set, this variable determines the pager to use for output by programs, such as man

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Question 13

Variable

PATH

Answer 13

This is an unusually important environment variable. It sets the path for a session, which is a colon-delimited list of directories

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Question 14

Variable

PS1

Answer 14

This is the default prompt in bash. It generally includes variables of its own, such as \u (username) \h (hostname), and \W (for profile)

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Question 15

Variable

PWD

Answer 15

This is the present working directory. This environment variable is maintained by the system. Programs may use it to search for files when you don’t provide a complete pathname

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Question 16

Variable

SHELL

Answer 16

holds the path to the current command shell

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Question 17

Variable

TERM

Answer 17

name of the current terminal type. To move display of text effects for programs like text-mode editors

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Question 18

Variable

TZ

Answer 18

Sets the environment variable to your own timezone which is most useful if that’s different than the computer’s time zone

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Question 19

Variable

USER

Answer 19

Current username. It’s a variable that’s maintained by the system

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Question 20

Variable

USERNAME

Answer 20

An alternative to the USER variable

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Question 21

Conditional Expression

Answer 21

enables a script to determine whether to follow a script based on a qualifier

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Question 22

user-defined variable

Answer 22

variable defined by a user for various purposes like storing data

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Question 23

writing a condition

Answer 23

use [ condition ]

the spaces are necessary! Linux is stupid!

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Question 24

elif

Answer 24

means “else if”

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Question 25

||

Answer 25

means or

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Question 26

For loop syntax

Answer 26

For variable in list
do
commands
done

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Question 27

sendmail

Answer 27

former dominant program for sending email server packages on the Internet. Still very powerful

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Question 28

Postfix

Answer 28

modular replacement for sendmail. Sendmail uses a single program to do everything, postfix uses multiple programs, each with its own specific small task

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Question 29

Exim

Answer 29

Like sendmail, but with a simpler configuration file format making it easier to configure

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Question 30

Qmail

Answer 30

4th major Linux email server. Modular server with security as a major design goal.

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Question 31

mail server options

-v

Answer 31

produces a verbose output. Helpful when debugging

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Question 32

mail server options

-s

Answer 32

subject option enables you to specify the subject line

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Question 33

mail server options

-f

Answer 33

to read your email.

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Question 34

Environmental Variables

Answer 34

means to pass names and data. Used to store information on the system for the benefit of running programs. There are over 40 default in the system.

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