Bash MCQ: Bash Multiple Choice Questions and Answers

Bash MCQ with answers and explanations for placement tests and job interviews. These solved Bash MCQs are useful for the campus placement for all freshers including Engineering Students, MCA students, Computer and IT Engineers, etc.

Our Bash MCQ (Bash Multiple Choice Questions ) focuses on various parts of the Bash shell and command language its concept. It will be useful for anyone learning Bash language Basics, Essentials, and/or Fundamentals. We will regularly update the quiz and most interesting thing is that questions come in a random sequence. So every time you will feel new questions.

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Guideline of Bash MCQ:

This Bash MCQ is intended for checking your Bash framework knowledge. It takes 1 hour to pass the Bash MCQ. If you don’t finish the Bash MCQ within the mentioned time, all the unanswered questions will count as wrong. You can miss the questions by clicking the “Next” button and return to the previous questions by the “Previous” button. Every unanswered question will count as wrong. MCQ on Bash has features of randomization which feel you a new question set at every attempt.

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Bash MCQ

Bash MCQ: Bash Multiple Choice Questions and Answers

1 / 53

What does the asterisk represent in this statement?

<em>#!/usr/bin/env bash</em>
case $num in
  1)
  echo "one"
  ; ;
  2)
  echo "two"
  ; ;
  *)
  echo "a mystery"
  ; ;
esac

a case only for what happens when the asterisk character is passed into the script

a case that matches any value, providing a default option if nothing else catches that value

the action of all of the other cases combined together

an action that is taken for any input, even if it matches a specified condition

2 / 53

Using "awk", what would the output of this command string be?

echo "1 2 3" | awk '{for (i=1; i<=NF; i++) s=s+$i};END {print s}'

123

600

3 / 53

In Bash, what does the comment below do?

cd -

It moves you to your home folder (whatever your current working directory happens to be).

It deletes the current directory

It moves you to the directory you were previously in.

It moves you one directory above your current working directory.

4 / 53

If file.sql holds SQL statements to be executed, what will be in file.txt?

mysql < file.sql > file.txt

a copy of the contents of file.sql

an error indicating that this is invalid syntax

the error output of the MySQL command

the non-error output of the MySQL command

5 / 53

Using Bash extended globbing, what will be the output of this command?

$ ls -l
apple
banana
bananapple
banapple
pineapple
strawberry
$ shopt -s extglob
$ ls -l @(ba*(na)|a+(p)le)

apple banana

apple banana bananapple

apple banana bananapple banapple

bananappple banapple pineapple

6 / 53

For the script to print "Is numeric" on screen, what would the user have to enter when prompted?

#!/bin/bash
read -p "Enter text " var
if [[ "$var" =~ "^[0-9]+$" ]];then
    echo "Is numeric"
else
    echo "Is not numeric"
fi

Any sequence of characters that includes an integer

The user would have to enter the character sequence of ^[0-9]]+$ Only this will prove to be true and "Is numeric" would be printed on the screen due to incorrect syntax. By encapsulating the regular expression in double quotes every match will fail except the text string ^[0-9]+$

Due to a syntax error it is impossible to get the script to print "Is numeric"

One or more characters that only includes integers

7 / 53

What would be in out.txt?

cat < in.txt > out.txt

Nothing. The redirect will create a new empty file but there will not be any output from the cat command to redirect.

It would be the contents of in.txt.

The output from the command line. By default STDIN comes from the keyboard.

Nothing because you can't redirect from file (in.txt) to another file (out.txt). You can only redirect from a command to a file.

8 / 53

In order for a Bash script to be executed like an OS command, it should start with a shebang line. What does this look like?

'$!/usr/bin/env bash

~/usr/bin/env bash

#!/usr/bin/env bash

#/usr/bin/env bash

9 / 53

What is the keyboard shortcut to call up the Bash history search as shown below?

(reverse-i-search)

Esc + R

Ctrl + H

Ctrl + R

Alt + R

10 / 53

In order to extract text from the first column of file called textfile, which command would you use?

cat {$1,textfile}

cat textfile | awk [print $1]

cat textfile | awk '{print $1}'

awk textfile {print $1}

11 / 53

What happens if you use the "set -e" in a Bash script?

It will cause Bash to exit if a function or subshell returns a nonzero status code.

It will cause Bash to exit if a conditional returns a non-zero status code.

It will cause Bash to exit if local, declare, or typeset assignments return a nonzero status code.

It will cause Bash to exit if a command, list of commands, compound command, or potentially a pipeline returns a nonzero status code.

12 / 53

To permanently remove empty lines from a file called textfile, which command could you use?

sed '/^$/d' textfile

sed -i 's/^$//' textfile

sed -i '/^$/d' textfile

cat textfile | sed '/^$/d

13 / 53

Suppose your current working directory is your home directory. How could you run the script demo.sh that is located in your home directory? Find three correct answers.

A. /home/demo.sh
B. ./demo.sh
C. ~/demo.sh
D. bash /home/demo.sh
E. bash demo.sh

A, B, C

B, C, E

B, D, E

C, D, E

14 / 53

Which file allows you to save modifications to the shell environment across sessions?

/etc/bash.conf

~/.profile

/etc/bashprofile

~/profile

15 / 53

What happens if you use the "set -e" in a Bash script?

It will cause Bash to exit if a function or subshell returns a nonzero status code.

It will cause Bash to exit if a conditional returns a non-zero status code.

It will cause Bash to exit if local, declare, or typeset assignments return a nonzero status code.

It will cause Bash to exit if a command, list of commands, compound command, or potentially a pipeline returns a nonzero status code.

16 / 53

What do you use in a case statement to tell Bash that you're done with a specific test?

; ;

: :

done

17 / 53

What will be in out.txt?

ls nonexistentfile | grep "No such file" > out.txt

ls: cannot access nonexistentfile: No such file or directory

No such file

It will be the contents of nonexistentfile.

Nothing, out.txt will be empty

18 / 53

What is wrong with this script?

#!/bin/bash
read -p "Enter your pet type." PET
if [ $PET = dog ] ;then
    echo "You have a dog"
fi

If the value of PET doesn't match dog, the script will return a nonzero status code.

It will fail if the user hits the Enter (Return) key without entering a pet name when prompted.

The then statement needs to be on a separate line.

There is nothing wrong with it. The condition checks the value of PET perfectly.

19 / 53

In the script shown below, what is a greeting?

<em>#!/usr/bin/env bash</em>
greeting="Hello"
echo $greeting, everybody!

a loop

a vairable

a command

a parameter

20 / 53

Which statement checks whether the variable num is greater than five?

(( $num -gt 5 ))

[[$num -lt 5]]

(( $num > 5 ))

$num > 5

21 / 53

How does the SUID or setuid affect executable commands?

When the command creates files, they will be owned by the group owner of the command.

The SUID bit allows anyone to execute the command no matter what other permissions are set.

When the command is executed, its running privileges elevate to the user owner of the command.

When the command is executed, its running privileges elevate to the group owner of the command.

22 / 53

How would you find the last copy command run in your history?

history | grep cp

grep cp history

history | find cp

cp history

23 / 53

Which command is being run in this script to check if file.txt exists?

if [ -f file.txt ]; then
    echo "file.txt exists"
fi

/usr/bin/test

/usr/bin/[

the built-in [ command

/usr/bin/[[

24 / 53

Assuming that user1 existed, what would be the result of this command string?

awk -F: '/user1/{print $1 "-" $3 "-" $6}' /etc/passwd

It would show the username, UID, and home directory of user1 separated by colons.

It would print the UID, GID, and home directory of user1 separated by hyphens.

It would print the UID, comment, and home directory of user1 separated by hyphens.

It would show the username, UID, and home directory of user1 separated by hyphens.

25 / 53

What is the result of this script?

txt=Penguins
[[ $txt =~ [a-z]{8} ]]; echo $?

0, representing 'true', because the variable "txt" contains eight letters

0, representing 'true', because everybody loves penguins!

1, representing 'false', because the variable "txt" is longer than eight characters

1, representing 'false', because the variable "txt" does not contain eight lowercase letters between a and z

26 / 53

What file would match the code below?

ls Hello[[.vertical-line.]]World

Hello.vertical-line.World

Hello[[.vertical-line.]]World

Hello|World

Nothing, this is an invalid file glob.

27 / 53

How could you get a list of all .html files in your tree?

find *.html

find . -name *.html

find . -type html

find . -name \*.html -print

28 / 53

The **\_\_** keyword pauses the script to get input from standard input.

get

argument

read

input

29 / 53

What is the output of this code?

VAR="/var/www/html/website.com/html/"
echo "${VAR#*/html}"

/website.com/html/

/html/website.com/html/

/var/www/html/website.com/

Nothing will be echoed on the screen.

30 / 53

To run a copy command in a subshell, which syntax would you use?

( command )

sh command

{ command; }

(( command ))

31 / 53

What does the + signify at the end of the 10-digit file permissions on data.txt?

ls -l
-rwx------+ 1 user1 u1 0 Oct 1 10:00 data.txt

There is an SELinux security context

There is an access control list

The sticky bit is set and the file will stay in RAM for speed

There is an extended attribute such as immutable set

32 / 53

Given the listed permissions on data.txt is it possible that user2 could have read, write, and execute permissions on data.txt?

$ ls -l
total 0
-rwx------+ 1 user1 user1 0 Oct 27 10:54 data.txt

No, it's clear that user2 does not have read, write, and execute permissions.

Yes, the + at the end of the 10-digit permission string signifies there's an access control list. This could possibly give user2 permissions not visible by ls -l.

Yes, the + at the end of the 10-digit permission string signifies there's an extended attribute set. This could give user2 permissions to read, write, and execute data.txt.

It's possible that SELinux provides read, write, and execute permissions for user2 which are not visible with ls -l.

33 / 53

In order to write a script that iterates through the files in a directory, which of the following could you use?

bash for i in $(ls); do ... done

bash for $(ls); do ... done

bash for $ls; do ... done

bash for i in $ls; do ... done

34 / 53

What is the output of:

VAR="This old man came rolling"
echo "\${VAR//man/rolling}"

This old man came man

This old man came rolling

This old rolling came rolling

This old came

35 / 53

What does this script accomplish?

#!/bin/bash
declare -A ARRAY=([user1]=bob [user2]=ted [user3]=sally)
KEYS=(${!ARRAY[@]})

for (( i=0; $i < ${#ARRAY[@]}; i+=1 ));do
        echo ${KEYS[$i]} - ${ARRAY[${KEYS[$i]}]}
done

Using a C-style for loop, it loops through the associative array named ARRAY using the associative array's keys and outputs both the key and values for each item.

It creates an indexed array of the associative array named ARRAY. It then uses a C-style for loop and the indexed array to loop through all items in the associative array, outputting the key and value of each array item using the index number.

It creates an associative array named ARRAY, which it loops through using a C-style for loop and the index numbers of each item in the associative array's keys, outputting the value of each item.

It sorts the associative array named ARRAY and stores the results in an indexed array named KEYS. It then uses this sorted array to loop through the associative array ARRAY.

36 / 53

What is the output of this script?

#!/bin/bash
fname=john
john=thomas
echo ${!fname}

john

thomas

Syntax error

blank

37 / 53

If script.sh is run in the current directory, it will fail. Why?

$ ls -1
Beach photo1.jpg
Photo1.jpg
Photo2.jpg
Script.sh

$ cat script.sh
for i in $(ls *.jpg); do
  mv $i ${i}.bak
done

ls: cannot access nonexistentfile: No such file or directory

The for loop will split on word boundaries and Beach photo1.jpg has a space in it.

The mv command will fail because the curly bracket is a special character in Bash and cannot be used in the names of files.

Running script.sh will be successful as the ls command builds a list of files in the current directory and for loops through that list renaming files with a .bak extension.

38 / 53

If prompted for text at the standard input, you can tell the command you're done entering text with what key combination?

Ctrl + A (Windows) or Command + A (Mac)

Ctrl + E (Windows) or Command + E (Mac

Ctrl + D (Windows) or Command + D (Mac)

Ctrl + Z (Windows) or Command + Z (Mac

39 / 53

How can you gather history together for multiple terminals?

It just works by default.

history --shared

shopt -s histappend

history --combined

40 / 53

Which variable would you check to verify that the last command executed successfully?

41 / 53

What will be the output of this script?

#!/bin/bash
Linux=('Debian' 'Redhat' 'Ubuntu' 'Android' 'Fedora' 'Suse')
x=3

Linux=(${Linux[@]:0:$x} ${Linux[@]:$(($x + 1))})
echo "${Linux[@]}"

Debian Redhat Ubuntu Android Fedora Suse

Fedora Suse

Android

Debian Redhat Ubuntu Fedora Suse

42 / 53

What does this command do?

cat > notes -

Accepts text from standard input and places it in "notes"

Creates "notes" and exits

Appends text to the existing "notes"

Outputs the content of notes and deletes it

43 / 53

What is the difference between the $@ and $* variables?

$@ treats each quoted argument as a separate entity. $* treats the entire argument string as one entity.

$* treats each quoted argument as a separate entity. $@ treats the entire argument string as one entity.

$* is used to count the arguments passed to a script, $@ provides all arguments in one string.

$* is the wildcard that includes all arguments with word splitting, $@ holds the same data but in an array.

44 / 53

How would you change your Bash shell prompt to the following?

HAL>

SHELL="HAL\>"

SHELL="HAL>"

export PS1="HAL>"

PS1="HAL\>"

45 / 53

Which arithmetic expression will give the most precise answer?

var=$( expr 10 / 8 )

(( var= 10 /8 ))

var=$(( 10 / 8 ))

var=$(echo 'scale=2; 10 / 8' | bc)

46 / 53

When used from within a script, which variable contains the name of the script?

$@ // array-like construct of all positional parameters

$$ // pid of the current shell

$# // number of positional parameters

47 / 53

The command below will search the root filesystem for files named "finance.db". In this context, what information is being sent to /dev/null?

find / -name "finance.db" 1>results.txt 2>/dev/null

the names of files that do not match finance.db

information sent to the standard error-for example, errors that the find command displays as it runs

the names of files that match finance.db

information sent to the standard output-that is, the path to files the find command has located

48 / 53

What will be the difference between the output on the screen and the contents of out.txt

mysql < file.sql > out.txt

The output on the screen will be identical to out.txt

There will be no output on the screen as it's being redirected to out.txt.

The out.txt file will hold STDERR and STDOUT will go to the screen.

The output on the screen will be identical to out.txt plus line numbers.

49 / 53

What does this bash statement do?

(( $a == $b ))
echo $?

It loops between the values of $a and $b.

It tests whether the values of variables $a and $b are equal.

It returns $b if it is larger than $a

It returns $a if it is larger than $b

50 / 53

When executing a command and passing the output of that command to another command, which character allows you to chain these commands together?

51 / 53

Which of the three methods will copy the directory named "photo dir" recursively from the user's home directory to /backups?

cp -R "~/photo dir" /backups #method1
cp -R ~"/photo dir" /backups #method2
cp -R ~/"photo dir" /backups #method3

None of the three methods will expand to the user's home directory. Only using "$HOME/photo dir"will be successful.

Only method 1 will expand "~/" to the user's home directory and then append the quoted directory name that includes a space.

Only method 2 will expand "~/" to the user's home directory and then append the quoted directory name that includes a space.

Only method 3 will expand "~/" to the user's home directory and then append the quoted directory name that includes a space.

52 / 53

What line of Bash script probably produced the output shown below?

The date is: Sun Mar 24 12:30:06 CST 2019!

echo "The date is: date!"

echo "The date is: !"

echo "The date is: $(date)!"

echo "The date is: (date)!"

53 / 53

What Bash script will correctly create these files?

touch file{1+10}.txt

touch file{1-10}.txt

touch file{1..10}.txt

None of the above

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Bash MCQ: Bash Multiple Choice Questions and Answers

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