Linux 2 Ch 1- Adv shell features

Question 1

&&

Answer 1

This is an AND list. If the command on the left side of && does execute successfully, then the command on the right side of && will execute.

Question 2

.

Answer 2

Command used to re-execute a bash shell configuration file (.profile, .bashrc, etc.) after changes are made.

Question 3

/etc/bash.bashrc

Answer 3

Systemwide configuration file read when a new shell starts. Contains variables, commands, and aliases common to all users.

Question 4

/etc/profile

Answer 4

Systemwide bash configuration file read at login. Contains bash settings and environment variables common to all users.

Question 5

A function is given 3 arguments as input. The third argument of a function is identified as:
$1
$3
$PATH
$arg3

Answer 5

$3

Question 6

A login BASH shell executes which of the following additional files (compared to an interactive BASH shell)?
/etc/profile and either ~/.bash_profile or ~/.bash_login or ~/.profile
/etc/profile and ~/.bashrc
/etc/profile and /etc/bashrc
~/.bash_profile and ~/.bashrc.

Answer 6

/etc/profile and either ~/.bash_profile or

Question 7

alias

Answer 7

alias and unalias utilities create or remove a nickname (shorthand term) for a command or series of commands.

Question 8

Changes in the __________ initialization file will affect all the users on the system.
Local
Shell
Network
Global

Answer 8

Global

Question 9

Defining the PS1 variable in an initialization file will not make changes to the prompt persistent between logins.
True or False?
True
False

Answer 9

False

Question 10

env

Answer 10

Displays all environmental variables available to all shells.

Question 11

export

Answer 11

With no arguments export displays all environmental variables available to all shells. export VARIABLE is used to export a locl variable.

Question 12

function

Answer 12

Similar to an alias but for executing multiple commands. Typically used in bash shell scripts.

Question 13

Once a variable is declared, it cannot be deleted.
True or False?

Answer 13

False

Question 14

set

Answer 14

With no arguments set displays the values of all variables (local and environment) set in the current shell

Question 15

source

Answer 15

Command used to re-execute a bash shell configuration file (.profile, .bashrc, etc.) after changes are made.

Question 16

Sourcing is an effective way to test initialization file changes. Which of the following is used to source a file?
None of the above
The touch command
Either the period . character or the source command
The tilde ~ character

Answer 16

Either the period . character or the source command

Question 17

The ___________ command can be used to check if a command already exists.
command
type
ex
check

Answer 17

type

Question 18

The best way to group multiple commands and pass arguments is to:
Concatenate them
Use functions
Create an initialization file
Create an alias

Answer 18

Use functions

Question 19

unset

Answer 19

Removes the variable from the current shell and subshells.

Question 20

Which of the following is not a valid option for executing a command that is not in the directories listed in the PATH variable?
Add the directory containing the command to the PATH variable
Copy the command to a directory listed in the PATH
By typing the absolute or relative path to the command
Rename the command and its directory

Answer 20

Rename the command and its directory

Question 21

Which script is executed when you exit the shell?
~/.bashrc
/etc/bashrc
~/.bash_profile
~/.bash_logout

Answer 21

~/.bash_logout

Question 22

||

Answer 22

This is an OR list. If the command on the left side of || does NOT execute successfully, then the command on the right side of || is executed.

Question 23

~/.bash_login

Answer 23

A bash user configuration file used to customize the shell environment. Sourced if ~/.bash_profile does not exist. Includes global variables not defined in /etc/profile.

Question 24

~/.bash_logout

Answer 24

A bash user configuration file read at logout. Typically contains “clean up” commands such as clear to remove any text on the screen.

Question 25

~/.bash_profile

Answer 25

A bash user configuration file used to customize the shell environment. If exists, it is sourced after /etc/profile. Includes global variables not defined in /etc/profile

Question 26

~/.bashrc

Answer 26

A bash user configuration file read each time a new shell is started. Typically contains local variables, commands and aliases.

Question 27

~/.profile

Answer 27

A bash user configuration file used to customize the shell environment. Sourced if neither ~/.bash_profile or ~/.bash_login does not exist. Includes global variables not defined in /etc/profile.

Question 28

Command for the current desktop

Answer 28

echo $XDG_CURRENT_DESKTOP