Running scripts in Bash Scripting - Mini Project: Build & Apply

Running Bash Scripts

📖 Scenario: You want to automate a simple task on your computer using a Bash script. This script will greet you and show the current date and time.

🎯 Goal: Create a Bash script file, make it executable, and run it to see the greeting and current date and time.

📋 What You'll Learn

Create a Bash script file named greet.sh.

Write a script that prints a greeting message and the current date and time.

Make the script executable using the correct command.

Run the script and display its output.

💡 Why This Matters

🌍 Real World

Running scripts is a basic way to automate tasks on your computer, like backups, reminders, or system checks.

💼 Career

Many IT and developer jobs require writing and running scripts to save time and reduce errors.

1

Create the Bash script file

Create a file named greet.sh and add the first line #!/bin/bash to specify the script interpreter.

Bash Scripting

# Create the greet.sh file and add the shebang line
# Your code here

Hint

The first line of a Bash script should be #!/bin/bash to tell the system to use Bash to run it.

2

Add greeting and date commands

Add two lines to greet.sh: one to print Hello, welcome! using echo, and one to print the current date and time using the date command.

Bash Scripting

#!/bin/bash
# Add echo and date commands below
# Your code here

Hint

Use echo "Hello, welcome!" to print the greeting and date to show the current date and time.

3

Make the script executable

Use the command chmod +x greet.sh to make the script file executable.

Bash Scripting

#!/bin/bash
echo "Hello, welcome!"
date
# Make greet.sh executable
# Your code here

Hint

Use chmod +x greet.sh in the terminal to allow running the script.

4

Run the script and display output

Run the script by typing ./greet.sh in the terminal and print the output.

Bash Scripting

#!/bin/bash
echo "Hello, welcome!"
date

# Run the script with ./greet.sh
# Your code here

Hint

Run ./greet.sh in the terminal. You should see the greeting and the current date and time.

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