LINUX: Shell Scripting Exercises

Note : These exercises are from “Linux Training Academy’s” Shell Scripting course.

Exercise 1: Write a shell script that prints “Hello World!” to the screen.

Hint 1: Remember to make the shell script executable with the chmod command.
Hint 2: Remember to start your script with a shebang!

#!/bin/bash
echo "Hello World!"

Exercise 2: Modify the shell script from exercise 1 to include a variable. The variable will hold the contents of the message “Hello World!”.

#!/bin/bash
THE_MESSAGE="Hello World!"
echo "$THE_MESSAGE"

Exercise 3: Store the output of the command “hostname” in a variable. Display “This script is running on .” where “ “ is the output of the “hostname” command.

Hint: It’s a best practice to use the ${VARIABLE} syntax if there is text or characters that directly precede or follow the variable.

#!/bin/bash
THE_HOSTNAME=$(hostname)
echo "The script is running on $THE_HOSTNAME"

Exercise 4: Write a shell script to check to see if the file “/etc/shadow” exists. If it does exist, display “Shadow passwords are enabled.” Next, check to see if ou can write to the file. If you can, display “You have permissions to edit /etc/shadow.” If you cannot, display “You do NOT have permissions to edit /etc/shadow.”

#!/bin/bash

THE_PATH="/etc/shadow"

if [ -e $THE_PATH ]
then
     echo "Shadow Passwords are enabled"

     if [ -w $THE_PATH ]
     then
          echo "You have permission to edit $THE_PATH"
     else
          echo "Tou do NOT have permission to edit $THE_PATH"
     fi
else
     echo "Shadow Passowrds not enabled"
fi

Exercise 5: Write a shell script that displays “man”, “bear”, “pig”, “dog”, “cat”, and sheep to the screen with each appearing on a separate line. Try to do this in as few lines as possible. Hint: Loops can be used to perform repetitive tasks.

#!/bin/bash

ANIMALS="man bear pig dog cat sheep"

for ANIMAL in $ANIMALS
do
        echo "$ANIMAL"
done

Exercise 6: Write a shell script that prompts the user for a name of a file or directory and reports if it is a regular file, a directory, or other type of file. Also perform an ls command against the file or directory with the long listing option.

#!/bin/bash

read -p "Enter a path for file/folder : " THE_PATH

if [ -d $THE_PATH ]
then
        echo "$THE_PATH is a directory"
elif [ -f $THE_PATH ]
then
        echo "$THE_PATH is a simple file"
elif [ -e $THE_PATH ]
then
        echo "$THE_PATH is not a simple file"
else
        echo "$THE_PATH does NOT exist!!"
fi

echo "$(ls -l $THE_PATH)"

Exercise 7: Modify the previous script so that it accepts the file or directory name as an argument instead of prompting the user to enter it.

#!/bin/bash

THE_PATH=$1

if [ -d $THE_PATH ]
then
        echo "$THE_PATH is a directory"
elif [ -f $THE_PATH ]
then
        echo "$THE_PATH is a simple file"
elif [ -e $THE_PATH ]
then
        echo "$THE_PATH is not a simple file"
else
        echo "$THE_PATH does NOT exist!!"
fi

echo "$(ls -l $THE_PATH)"

Exercise 8: Modify the previous script to accept an unlimited number of files and directories as arguments. Hint: You’ll want to use a special variable.

#!/bin/bash

for THE_PATH in $@
do
if [ -d $THE_PATH ]
then
        echo "$THE_PATH is a directory"
elif [ -f $THE_PATH ]
then
        echo "$THE_PATH is a simple file"
elif [ -e $THE_PATH ]
then
        echo "$THE_PATH is not a simple file"
else
        echo "$THE_PATH does NOT exist!!"
fi

echo "$(ls -l $THE_PATH)"

done