How to Run a Bash Script: Simple Steps and Examples

To run a bash script, use the command bash scriptname.sh or make the script executable with chmod +x scriptname.sh and run it with ./scriptname.sh. This executes the commands inside the script file in a bash shell.

Syntax

There are two main ways to run a bash script:

• Using bash command: Runs the script with the bash interpreter explicitly.
• Using executable permission: Makes the script file executable and runs it directly.

Syntax details:

• bash scriptname.sh: Runs the script with bash.
• chmod +x scriptname.sh: Adds execute permission.
• ./scriptname.sh: Runs the script if it has execute permission.

bash

bash scriptname.sh
chmod +x scriptname.sh
./scriptname.sh

Example

This example script prints a greeting message. It shows how to run a bash script using both methods.

bash

#!/bin/bash
# greeting.sh

echo "Hello, welcome to bash scripting!"

Output

Hello, welcome to bash scripting!

Common Pitfalls

Common mistakes when running bash scripts include:

• Not giving execute permission before running with ./scriptname.sh.
• Trying to run the script without specifying the interpreter if the shebang (#!/bin/bash) is missing.
• Running the script with ./ but the current directory is not in the PATH.

bash

# Wrong: Trying to run without execute permission
./greeting.sh

# Right: Add execute permission first
chmod +x greeting.sh
./greeting.sh

Quick Reference

Summary tips for running bash scripts:

• Use bash scriptname.sh to run without changing permissions.
• Use chmod +x scriptname.sh and ./scriptname.sh for direct execution.
• Always start scripts with #!/bin/bash for portability.
• Check file permissions with ls -l.

Key Takeaways

Run a bash script using bash scriptname.sh or make it executable and run with ./scriptname.sh.

Add execute permission with chmod +x scriptname.sh before running directly.

Include #!/bin/bash at the top of your script for proper interpreter usage.

Check and fix permissions if you get 'Permission denied' errors.

Use the current directory prefix ./ to run scripts not in your PATH.