First Basic Script

Create your first shell script step by step. Set executable permission using chmod. Run script in different ways. Common beginner mistakes and solutions.

What Is a Shell Script?

A shell script is a text file containing a sequence of Linux commands. These commands are executed line by line by the shell.

Scripts help automate tasks, reduce manual work, and ensure consistency across systems.

Why Execution Permission Matters

Linux treats scripts like normal files. To execute a script directly, it must have execute permission.

Without execute permission, the system will block execution for security reasons.

Script File

A plain text file containing shell commands.

Execution Permission

Required to run a script directly using ./script.sh.

Execution Methods

Run using ./script.sh, bash script.sh, or sh script.sh.

Step-by-Step: Create & Run Script

1. Create Your First Script File

Create a new file using a text editor. Here we use nano.

terminal — bash

first-script

nano hello.sh

2. Write Your First Script

Add a shebang and a simple echo command.

terminal — bash

first-script

#!/bin/bash
echo "Hello World from my first script"

3. Check File Permissions

By default, a new file does not have execute permission.

terminal — bash

first-script

ls -l hello.sh
-rw-r--r-- 1 user user 45 hello.sh

4. Give Execute Permission

Make the script executable using chmod.

terminal — bash

first-script

chmod u+x hello.sh
 
ls -l hello.sh
-rwxr--r-- 1 user user 45 hello.sh

5. Execute the Script

Run the script using ./ when it has execute permission.

terminal — bash

first-script

./hello.sh

6. Run Script Using Shell Command

You can also execute a script without execute permission.

terminal — bash

first-script

bash hello.sh
sh hello.sh

Common Mistakes Beginners Make

Avoid These Issues

Forgetting to add execute permission.
Typing ./script.sh without execute permission.
Using Windows line endings (CRLF).
Missing or incorrect shebang line.

Practice Task – Your First Script

Create a script named hello.sh.
Add a shebang and print your name.
Give execute permission.
Run it using ./hello.sh.
Try running with bash hello.sh.

Next lesson: Variables in Shell Scripting