How to Run a Bash Script in Linux

If you use Linux, learning to run bash scripts is an important skill. Bash scripts help you automate tasks, manage your system, and make your work easier. There are a few ways to run a bash script, and the best method depends on what you need.

This article explains the different methods for running bash scripts in Linux and how to resolve common issues. If you’re new to Linux, start with our guide on basic Linux commands .

Making a Script Executable #

The most common way to run a bash script is to make it executable and run it directly.

First, at the top of your script, add a shebang line that tells the system which interpreter to use:

#!/bin/bash

echo "Hello, World!"

Use chmod to make the script executable:

chmod +x script.sh

Now run the script by typing ./ followed by the script name:

./script.sh

Hello, World!

The ./ tells the shell to look for the script in the current directory.

Running a Script with the Bash Interpreter #

You can run a script by explicitly calling the bash interpreter. This method doesn’t require the script to be executable:

bash script.sh

This is handy if you can’t change file permissions or just want to test a script quickly.

You can also use sh for POSIX-compatible scripts:

sh script.sh

Sourcing a Script (Run in the Current Shell) #

Sourcing a script runs it in the current shell session, not in a subshell. Use the source command or its shorthand .:

source script.sh

Or:

. script.sh

This is useful when the script sets environment variables or defines functions that you want to use in your current shell.

For example, if you have a script that sets a variable:

#!/bin/bash
export MY_VAR="Hello"

When running normally, the variable is not available in the current shell:

./setenv.sh
echo $MY_VAR

When sourcing, the variable persists:

source setenv.sh
echo $MY_VAR

Hello

Running Scripts in the Background #

To run a script in the background , append & to the command:

./script.sh &

For long-running scripts that should continue after you log out, use nohup :

nohup ./script.sh &

Running Scripts with Debug Mode #

To debug a script and see each command before it executes, use the -x flag:

bash -x script.sh

+ echo 'Hello, World!'
Hello, World!

Other useful Bash flags include:

• bash -n script.sh - Check syntax without running
• bash -v script.sh - Print lines as they are read
• bash -e script.sh - Exit immediately on error

Running Scripts from Anywhere #

To run a script from any directory, you can either specify the full path or add the script to a directory in your $PATH .

A common approach is to create a ~/bin directory:

mkdir -p ~/bin

Add it to your ~/.bashrc:

export PATH="$HOME/bin:$PATH"

Move your script there and make it executable:

mv script.sh ~/bin/
chmod +x ~/bin/script.sh

After reloading your shell or running source ~/.bashrc, you can run the script from anywhere:

script.sh

Using /usr/bin/env in the Shebang (Best Practice) #

Instead of hardcoding the Bash path, you can use:

#!/usr/bin/env bash

echo "Hello, World!"

This approach is considered best practice because it works across different systems and respects the user’s environment.

Common Errors #

Permission Denied #

bash: ./script.sh: Permission denied

Make the script executable:

chmod +x script.sh

Command Not Found #

bash: script.sh: command not found

Use ./ prefix or provide the full path:

./script.sh

Bad Interpreter #

bash: ./script.sh: /bin/bash^M: bad interpreter

The file has Windows line endings. Convert it using:

sed -i 's/\r$//' script.sh

Security Considerations #

• If you downloaded a script from the Internet, always check its contents before running it.
• Be extra careful when running scripts as root.
• Use restrictive permissions when you can.
• Don’t add the current directory (.) to $PATH.
• Don’t run a script unless you’re sure it’s safe.

Conclusion #

There are several ways to run bash scripts in Linux. The most common is to make the script executable with chmod +x and run it using ./script.sh. You can also run scripts with the bash interpreter or source them if you want to change your current shell.

If you have questions or feedback, please leave a comment.