Simple BASH Scripts

Summary

A simple BASH script is a plain text file that contains one or more commands you would normally type at the command prompt. Instead of typing the same commands again and again, you can save them in a script and run the script as one command.

Basic script structure

For all descriptions below, the dollar sign indicates the BASH command prompt.

A very simple BASH script looks like this:

#!/usr/bin/env bash
echo "Hello from my first BASH script!"

The first line is called the “shebang” and tells the system to use bash to run the file.
The rest of the lines are normal BASH commands.

Creating and running a script

To create a new script file, you can use a text editor such as nano:

$ cd ~
$ nano hello.sh

Inside the file, type:

#!/usr/bin/env bash
echo "Hello from my first BASH script!"

Save and exit the editor.

Now you have a file called hello.sh in your home directory.

Next step, You must give it execute permission so that the system can run it as a program:

$ chmod +x hello.sh

You can run the script by calling bash directly:

$ bash hello.sh

Output

Hello from my first BASH script!

Using tab completion with script

After create and save a script file (for example hello.sh), you can already use tab completion on its name if you are in the same directory as the file.

For example, if ran:

$ nano hello.sh
$ chmod +x hello.sh

and you are still in the directory that contains hello.sh, you can type:

$ bash hel<Tab>

The shell will complete this to:

$ bash hello.sh

This method will save you time when naming different scripts.

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