Running scripts in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this script execution command?

You have a script named hello.sh with the following content:

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

What will be the output if you run bash hello.sh in the terminal?

Bash Scripting

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

A bash: hello.sh: command not found

B Hello, world!

C No output, script runs silently

D Error: Permission denied

💡 Hint

Running a script with bash executes the commands inside it and prints output.

Using bash hello.sh runs the script with bash interpreter, printing the echo output.

💻 Command Output

intermediate

What happens when you run a script without execute permission?

You have a script myscript.sh with content:

#!/bin/bash
echo "Run me!"

The file does NOT have execute permission. What happens if you run ./myscript.sh?

Bash Scripting

#!/bin/bash
echo "Run me!"

A bash: ./myscript.sh: Permission denied

B Run me!

C No output, script runs silently

D bash: myscript.sh: command not found

💡 Hint

Trying to run a file without execute permission causes a permission error.

Without execute permission, the shell refuses to run the script directly and shows a permission denied error.

📝 Syntax

advanced

Which command correctly runs a script named script.sh located in the current directory?

You want to run script.sh from the terminal. Which command will run it correctly assuming it has execute permission?

A script.sh

B bash ./script.sh

C /script.sh

D ./script.sh

💡 Hint

Scripts in the current directory need a path prefix to run directly.

To run a script in the current directory, you must prefix it with ./ to specify the path.

🔧 Debug

advanced

Why does this script fail to run with ./runme.sh?

Script runme.sh content:

echo "Start"
echo "Done"

You try ./runme.sh but get:
bash: ./runme.sh: Permission denied
What is the cause?

A The script lacks execute permission

B The script has a syntax error

C The script file is empty

D The script is missing the shebang line

💡 Hint

Permission denied means the OS won't let you run the file.

Without execute permission, the OS blocks running the script even if the content is valid.

🚀 Application

expert

What is the output of this script execution with environment variable?

Given the script envtest.sh:

#!/bin/bash
echo "User is: $USER"

You run:
USER=guest ./envtest.sh
What is the output?

Bash Scripting

#!/bin/bash
echo "User is: $USER"

A User is: (empty line)

B User is: $USER

C User is: guest

D bash: ./envtest.sh: Permission denied

💡 Hint

Setting an environment variable before a command overrides it inside the script.

The USER variable is set to guest only for the script execution, so it prints that value.

Practice

1. What is the correct way to run a bash script named myscript.sh after making it executable?

easy

A. Use ./myscript.sh to run the script.

B. Use run myscript.sh to run the script.

C. Use execute myscript.sh to run the script.

D. Use start myscript.sh to run the script.

Solution

1. Step 1: Understand script execution permission

   Before running a script with ./myscript.sh, it must have execute permission set using chmod +x myscript.sh.

2. Step 2: Run the script using relative path

   Using ./myscript.sh runs the script in the current directory. Other commands like run, execute, or start are not valid bash commands.

3. Final Answer:

   Use ./myscript.sh to run the script. -> Option A

4. Quick Check:

   Executable script run with ./script.sh = A [OK]

Hint: Make script executable, then run with ./script.sh [OK]

Common Mistakes:

• Trying to run script without execute permission
• Using invalid commands like run or start
• Not specifying path to script

2. Which of the following is the correct syntax to run a bash script named backup.sh without changing its permissions?

easy

A. ./backup.sh

B. sh run backup.sh

C. bash backup.sh

D. execute backup.sh

Solution

1. Step 1: Understand running scripts without execute permission

   If the script is not executable, you can run it by explicitly calling the shell interpreter like bash backup.sh.

2. Step 2: Identify correct syntax

   bash backup.sh runs the script using bash without needing execute permission. Other options either require execute permission or are invalid commands.

3. Final Answer:

   bash backup.sh -> Option C

4. Quick Check:

   Run script with interpreter command = B [OK]

Hint: Use bash script.sh to run without execute permission [OK]

Common Mistakes:

• Trying to run with ./ without execute permission
• Using invalid commands like execute
• Adding extra words like 'run' before script name

3. Given the script hello.sh with content:

#!/bin/bash
echo "Hello, $1!"

What is the output of ./hello.sh World?

medium

A. Hello, $1!

B. Hello, World!

C. Hello, !

D. Syntax error

Solution

1. Step 1: Understand script parameter usage

   The script uses $1 which is the first argument passed to the script. Here, World is passed as the first argument.

2. Step 2: Predict output after substitution

   The echo command prints "Hello, World!" by replacing $1 with the argument.

3. Final Answer:

   Hello, World! -> Option B

4. Quick Check:

   Argument $1 replaced by 'World' = A [OK]

Hint: Arguments like $1 print passed values in scripts [OK]

Common Mistakes:

• Printing literal $1 instead of argument
• Missing argument causing empty output
• Assuming syntax error due to shebang

4. You try to run a script with ./myscript.sh but get Permission denied. What is the most likely fix?

medium

A. Add execute permission with chmod +x myscript.sh.

B. Run the script with ./myscript.sh again.

C. Rename the script to myscript.sh.sh.

D. Delete the script and create a new one.

Solution

1. Step 1: Identify cause of 'Permission denied'

   This error usually means the script file does not have execute permission.

2. Step 2: Fix permission issue

   Use chmod +x myscript.sh to add execute permission, allowing the script to run.

3. Final Answer:

   Add execute permission with chmod +x myscript.sh. -> Option A

4. Quick Check:

   Permission denied fixed by chmod +x = D [OK]

Hint: Use chmod +x to fix permission denied errors [OK]

Common Mistakes:

• Trying to run script again without changing permissions
• Renaming script does not fix permissions
• Deleting script is unnecessary

5. You want to run a script deploy.sh located in /home/user/scripts from anywhere in the terminal without typing the full path. What is the best way to do this?

hard

A. Run the script with bash /home/user/scripts/deploy.sh every time.

B. Copy deploy.sh to /tmp directory.

C. Rename the script to deploy without extension.

D. Add /home/user/scripts to the PATH environment variable.

Solution

1. Step 1: Understand PATH environment variable

   PATH lists directories where the shell looks for commands. Adding a directory lets you run scripts inside it by name.

2. Step 2: Add script directory to PATH

   By adding /home/user/scripts to PATH, you can run deploy.sh from anywhere simply by typing deploy.sh.

3. Final Answer:

   Add /home/user/scripts to the PATH environment variable. -> Option D

4. Quick Check:

   PATH addition enables running scripts anywhere = C [OK]

Hint: Add script folder to PATH to run scripts anywhere [OK]

Common Mistakes:

• Copying script to /tmp is temporary and not recommended
• Running with full path every time is inconvenient
• Renaming script does not affect running from anywhere