Creating a script file (.sh) in Bash Scripting - Practice Exercises

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this script?

Consider this bash script saved as hello.sh and executed with bash hello.sh:

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

What will be printed on the terminal?

Bash Scripting

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

A Error: command not found

B hello world

C Hello, World!

D No output

💡 Hint

Look at the echo command and what it prints exactly.

The script uses echo to print the exact string "Hello, World!" including capitalization and punctuation.

📝 Syntax

intermediate

Which script has a syntax error?

Identify which of these bash scripts will cause a syntax error when run.

A

#!/bin/bash
while true; do echo "Loop"; break; done

B

#!/bin/bash
echo "Start"
if [ $1 -eq 1 ]; then echo "One" fi

C

#!/bin/bash
for i in 1 2 3; do echo $i; done

D

#!/bin/bash
echo "Done"

💡 Hint

Check if all if statements have proper closing keywords.

Option B is missing a semicolon or newline before 'fi', causing a syntax error.

🚀 Application

advanced

What does this script do?

Analyze this bash script and choose the correct description of its behavior:

#!/bin/bash
count=0
while [ $count -lt 3 ]; do
  echo "Count is $count"
  ((count++))
done
echo "Finished counting"

Bash Scripting

#!/bin/bash
count=0
while [ $count -lt 3 ]; do
  echo "Count is $count"
  ((count++))
done
echo "Finished counting"

A Prints 'Count is 0' three times then 'Finished counting'

B Infinite loop printing 'Count is 0'

C Prints 'Finished counting' only

D Prints 'Count is 0', 'Count is 1', 'Count is 2' then 'Finished counting'

💡 Hint

Look at the loop condition and how count changes.

The loop runs while count is less than 3, printing count values 0,1,2 then exits.

🔧 Debug

advanced

Why does this script fail to run?

This script is saved as myscript.sh and run with ./myscript.sh. It shows Permission denied. Why?

#!/bin/bash
echo "Running script"

A The script file does not have execute permission.

B The shebang line is incorrect.

C The echo command is misspelled.

D The script is missing a closing quote.

💡 Hint

Check file permissions with ls -l.

Without execute permission, the shell cannot run the script directly.

🧠 Conceptual

expert

What is the correct way to create a script file that runs on any bash shell?

You want to create a script file named runme.sh that works on any system with bash installed. Which option correctly creates and prepares this script?

A Create file with content starting with '#!/bin/bash', save it, then run 'chmod +x runme.sh' before executing.

B Create file with content starting with '#!/bin/sh', save it, then run 'chmod 644 runme.sh' before executing.

C Create file with content starting with '#!/bin/bash', save it, then run 'chmod 777 runme.sh' before executing.

D Create file with content starting with '#!/bin/bash', save it, then run 'chmod 600 runme.sh' before executing.

💡 Hint

The script needs execute permission and the correct shebang for bash.

Option A uses the correct shebang and sets execute permission properly without over-permission.

Practice

1. What is the main purpose of creating a .sh script file in bash?

easy

A. To compile programs

B. To store text documents

C. To save a list of commands to run them later easily

D. To create image files

Solution

1. Step 1: Understand what a script file is

   A .sh file contains bash commands saved to run multiple times without typing again.

2. Step 2: Identify the purpose of saving commands

   Saving commands helps automate tasks and avoid retyping, which matches To save a list of commands to run them later easily.

3. Final Answer:

   To save a list of commands to run them later easily -> Option C

4. Quick Check:

   Script file purpose = save commands [OK]

Hint: Scripts save commands to run anytime without retyping [OK]

Common Mistakes:

• Thinking .sh files are for text or images
• Confusing scripts with compiled programs
• Not knowing scripts automate commands

2. Which line should you add at the very top of a bash script file to specify the interpreter?

easy

A. #!/bin/python

B. #!/bin/bash

C. #!/usr/bin/node

D. #!/bin/shutdown

Solution

1. Step 1: Identify the correct shebang for bash scripts

   The shebang line tells the system which program runs the script. For bash, it is #!/bin/bash.

2. Step 2: Eliminate incorrect interpreters

   Options A, C, and D point to other interpreters or invalid commands.

3. Final Answer:

   #!/bin/bash -> Option B

4. Quick Check:

   Shebang for bash = #!/bin/bash [OK]

Hint: Use #!/bin/bash as first line to run bash scripts [OK]

Common Mistakes:

• Using wrong interpreter path
• Forgetting the #! at the start
• Confusing bash with other languages

3. What will be the output when you run this script named greet.sh?

#!/bin/bash
echo "Hello, $USER!"

medium

A. Syntax error

B. Hello, root!

C. Hello, $USER!

D. Hello, your-username!

Solution

1. Step 1: Understand the variable $USER in bash

   $USER is an environment variable that holds the current user's username.

2. Step 2: Predict the echo output

   The echo command prints "Hello, " followed by the username, so it outputs "Hello, your-username!" where your-username is the actual user.

3. Final Answer:

   Hello, your-username! -> Option D

4. Quick Check:

   $USER expands to username = Hello, your-username! [OK]

Hint: Variables like $USER show your username in scripts [OK]

Common Mistakes:

• Thinking $USER prints literally
• Expecting 'root' always
• Confusing syntax causing errors

4. You wrote a script myscript.sh but when you run ./myscript.sh, it says Permission denied. What is the likely fix?

medium

A. Run chmod +x myscript.sh to make it executable

B. Add #!/bin/bash at the top

C. Rename the file to myscript.txt

D. Run the script with bash myscript.sh only

Solution

1. Step 1: Understand the cause of 'Permission denied'

   This error usually means the file is not executable by the user.

2. Step 2: Make the script executable

   Using chmod +x myscript.sh adds execute permission, allowing ./myscript.sh to run.

3. Final Answer:

   Run chmod +x myscript.sh to make it executable -> Option A

4. Quick Check:

   Permission denied fix = chmod +x [OK]

Hint: Use chmod +x to allow script execution [OK]

Common Mistakes:

• Forgetting to make script executable
• Only adding shebang without permissions
• Renaming file instead of fixing permissions

5. You want to create a script backup.sh that prints "Backup started" and then lists files in the current directory. Which script content is correct?

hard

A. #!/bin/bash
echo "Backup started"
ls

B. echo "Backup started"
ls
#!/bin/bash

C. #!/bin/bash
echo Backup started
ls-l

D. #!/bin/sh
echo "Backup started"
list

Solution

1. Step 1: Check the shebang and commands order

   The script must start with #!/bin/bash to run in bash, then commands follow in order.

2. Step 2: Verify commands and syntax

   #!/bin/bash echo "Backup started" ls has correct shebang, echo with quotes, and ls command to list files. Others have wrong order, missing quotes, or invalid commands.

3. Final Answer:

   #!/bin/bash echo "Backup started" ls -> Option A

4. Quick Check:

   Correct script structure = #!/bin/bash echo "Backup started" ls [OK]

Hint: Start script with #!/bin/bash then commands line by line [OK]

Common Mistakes:

• Placing shebang after commands
• Using wrong commands like 'list'
• Missing quotes around strings