Bash MCQ: Bash Multiple Choice Questions and Answers

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?

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

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

HAL>

What would be in out.txt?

cat < in.txt > out.txt

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

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}'

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

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

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

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

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

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

What is the result of this script?

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

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

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

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

What is the output of:

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

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

mysql < file.sql > out.txt

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

In the script shown below, what is a greeting?

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

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

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

What is the output of this code?

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

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)

How can you gather history together for multiple terminals?

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

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

In Bash, what does the comment below do?

cd -

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

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

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

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

(reverse-i-search)

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

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

What does this bash statement do?

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

What Bash script will correctly create these files?

What will be in out.txt?

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

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

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

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

mysql < file.sql > file.txt

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

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

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

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

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

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

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

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

How does the SUID or setuid affect executable commands?

What is the output of this script?

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

What does this command do?

cat > notes -

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[@]}"

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

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

Which arithmetic expression will give the most precise answer?

What file would match the code below?

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