MODULE 5- Command line skills

Question 1

Which program receives user-entered commands in a terminal and translates them into actions for the operating system?

Answer 1

The shell, which interprets commands typed at the terminal and executes them.

Question 2

Which shell is the most commonly used one on Linux distributions and supports features like command history and inline editing?

Answer 2

The Bash shell (Bourne Again SHell).

Question 2

Which shell feature allows a user to run an entire series of commands from a text file, including logic and functions?

Answer 2

Scripting, which allows commands and logic to be executed from a file.

Question 3

Which shell feature allows creating nicknames for long or frequently-used commands?

Answer 3

Aliases, which act as shortcuts for longer commands.

Question 4

Which shell feature lets users and the system store information such as settings or data used during command execution?

Answer 4

Variables, which can store and retrieve information in the shell environment.

Question 5

Which term refers to a software program that performs an action when executed on the command line?

Answer 5

A command.

Question 6

Which command, when run with no options or arguments, lists the files and directories in the current working directory?

Answer 6

ls

Question 6

In the command syntax command [options] [arguments], which part is used to change how the command behaves?

Answer 6

Options

Question 6

In the command syntax command [options] [arguments], which part provides extra information like filenames or usernames?

Answer 6

Arguments.

Question 7

Which rule must always be followed when entering commands, filenames, or variables in a Linux terminal?

Answer 7

Linux is case-sensitive—inputs must be typed exactly as shown.

Question 7

Which symbol in the CLI represents the user’s home directory ?

Answer 7

The ~ symbol.

Question 7

How can you list the contents of both /etc/ppp and /etc/ssh in one command?

Answer 7

ls /etc/ppp /etc/ssh

Question 8

Which option of the ls command displays a long listing format with file permissions, ownership, and size?

Answer 8

-l

Question 8

Which option causes the ls command to reverse the order of the listing?

Answer 8

-r

Question 8

What does the command ls -lr display?

Answer 8

A long listing of files in reverse alphabetical order.

Question 9

What is the output of ls -lh /usr/bin/perl compared to ls -l /usr/bin/perl?

Answer 9

It shows the file size in human-readable format (e.g., 11K instead of 10376).

Question 10

What is the long-form equivalent of the -h option in ls?

Answer 10

(- -human-readable

Question 10

Which key can you press to cycle backward through previously executed commands?

Answer 10

Up Arrow (↑).

Question 11

Which command displays the list of commands executed in the current terminal session?

Answer 11

history

Question 11

Which keys allow editing of a recalled command by moving the cursor left or right?

Answer 11

Left Arrow (←) and Right Arrow (→).

Question 12

What command would display the last 3 commands executed in a session?

Answer 12

history 3

Question 13

Which symbol is used to re-execute a command by referencing its number in the history list?

Answer 13

! (exclamation mark).

Question 14

Which command would Re-execute command number 3 from the history list?

Answer 14

!3

Question 14

Which command would Re-execute the third command from the bottom of the history list?

Answer 14

!-3

Question 15

Which command re-executes the most recently run command?

Answer 15

!!

Question 16

Which command re-executes the most recent use of a specific command like ls?

Answer 16

!ls

Question 17

How do you view the history list without re-executing anything?

Answer 17

history

Question 18

Which type of variable exists only in the current shell session and disappears when the session ends?

Answer 18

Local variable

Question 19

Which type of variable is commonly used for user tasks and is written in lowercase by convention?

Answer 19

Local variable

Question 19

Which expression is used to assign a value to a variable in the shell?

Answer 19

variable=value

Question 20

What happens if a local variable already exists and is assigned a new value?

Answer 20

Its value is modified.

Question 21

Which command is used to display the value stored in a variable?

Answer 21

echo

Question 22

How do you reference the value of a variable when using the echo command?

Answer 22

By placing a $ before the variable name (e.g., $variable1)

Question 23

Which type of variable is available system-wide and persists across all Bash shells?

Answer 23

Environment variable (or global variable)

Question 24

What type of variable is PATH, HOME, or HISTSIZE an example of?

Answer 24

Environment variable

Question 25

Which environment variable controls how many previous commands are stored in the history list?

Answer 25

HISTSIZE

Question 26

Which command would you use to modify an environment variable named HISTSIZE to store only 500 commands?

Answer 26

HISTSIZE=500

Question 27

Which command outputs the full list of environment variables in the current shell?

Answer 27

env

Question 28

What command structure would you use to filter the output of env to search for a specific variable?

Answer 28

env | grep variable_name

Question 29

What is the result of running env | grep variable1 if variable1 is only a local variable?

Answer 29

No output

Question 30

Which command is used to convert a local variable into an environment variable?

Answer 30

export variable

Question 31

Which command both creates and exports a variable in a single step?

Answer 31

export variable2='Else'

Question 32

Which command allows a variable to be modified by concatenating its value with another variable's value?

Answer 32

variable1=$variable1' '$variable2

Question 33

Which command is used to remove an exported variable from the environment?

Answer 33

unset variable_name

Question 34

Which environment variable defines the directories Bash searches for commands?

Answer 34

PATH

Question 35

What character is used to separate directories in the PATH variable?

Answer 35

Colon (:)

Question 36

What does the following command do? PATH=/usr/bin/custom:$PATH

Answer 36

It prepends /usr/bin/custom to the PATH, keeping existing directories.

Question 37

Which command shows whether another command is built-in, external, or something else?

Answer 37

type

Question 38

Which command shows the exact path of a command as found in the PATH variable?

Answer 38

which

Question 38

If a command like echo exists both as a shell builtin and in /bin/, how can you see both versions?

Answer 38

type -a echo

Question 39

Which option of the type command displays all locations for a command name?

Answer 39

-a

Question 40

If the output of a command is /usr/bin/command, what kind of command is it?

Answer 40

External command

Question 41

If a command doesn't work and you suspect it's overridden by a function or alias, which command helps check?

Answer 41

type

Question 42

Which shell feature allows grouping multiple commands into a reusable block under a custom name?

Answer 42

Function

Question 42

What command creates an alias named mycal for cal 2019?

Answer 42

alias mycal="cal 2019"

Question 42

Which feature allows you to assign a short name to a longer command for faster access?

Answer 42

Alias

Question 43

What command shows all aliases currently set in the shell session?

Answer 43

alias

Question 43

If alias l='ls -CF' is set, what command is executed when you type l?

Answer 43

ls -CF (combo output and sort by file type)

Question 44

What does the following command do? alias grep='grep --color=auto'

Answer 44

Enhances the grep command to always highlight matches with color

Question 44

What command checks whether ll is an alias or something else?

Answer 44

type ll

Question 45

What do the curly braces {} in a function definition indicate?

Answer 45

They enclose the beginning and end of the function body

Question 45

What is the syntax used to define a Bash function called greet?

Answer 45

greet () { commands }

Question 46

Which type of quotes prevent glob characters from being expanded into filenames?

Answer 46

Double quotes (")

Question 47

Which characters are considered glob characters in Bash?

Answer 47

Asterisk (*), question mark (?), and square brackets ([ ])

Question 48

What do we call the Shell behavior where wildcard characters match files or patterns

Answer 48

globbing

Question 49

Which type of quotes prevent the shell from interpreting any special characters, including variables and globs?

Answer 49

Single quotes (')

Question 50

How can you prevent the $ symbol from being treated as a variable indicator while still using double quotes?

Answer 50

Use a backslash ( \ ) before the dollar sign: \$

Question 51

When inside single quotes, can the shell interpret metacharacters like *, ?, or $?

Answer 51

No, everything inside is treated literally

Question 52

Which special characters are used to perform command substitution in the Bash shell?

Answer 52

Backquotes (`)

Question 53

Which symbol is used to separate multiple commands so they run consecutively regardless of each other's success?

Answer 53

Semicolon (;)

Question 53

Which symbol is used to run a second command only if the first command is successful?

Answer 53

Double ampersand (&&)

Question 54

What is the behavior of the && operator between commands?

Answer 54

The second command runs only if the first command succeeds.

Question 55

What happens if command1 fails in a command1 && command2 structure?

Answer 55

command2 does not run

Question 56

Which symbol is used to run a second command only if the first command fails?

Answer 56

Double pipe (||)

Question 56

What is the behavior of the || operator between commands?

Answer 56

The second command runs only if the first command fails.

Question 56

How would you write a command that displays "Error!" only if cat file.txt fails?

Answer 56

cat file.txt || echo "Error!"

Question 57

Which command displays the username of the current user?

Answer 57

Whoami

Question 57

Which command shows name of kernel currently being used?

Answer 57

uname

Question 58

Which command is used to show the network node hostname ?

Answer 58

uname -n

Question 58

Which command is used to clear the screen?

Answer 58

clear

Question 59

Which command is used to display the last five commands from your history?

Answer 59

history 5

Question 60

For which type of commands does the type command display the location of the command?

Answer 60

External commands

Question 61

Which character prevents the shell from interpreting all special characters?

Answer 61

(') single quote

Question 61

Which character prevents the shell from interpreting glob character?

Answer 61

('') double quotes

Question 62

Which character causes command substitution?

Answer 62

(`) backquotes

Question 63

Which character prevents the shell from interpreting a single character?

Answer 63

(\) backslash

Question 64

Which other method besides using a backquote is useful for command substitution?

Answer 64

$(command)

Question 64

What do you do if you do not want the backquotes to be used to execute a command?

Answer 64

Place single quotes around them

Question 64

Which characters create a logical "and" statement?

Answer 64

&&

Question 65

Which characters characters create a logical "or" statement?

Answer 65

||