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Bash Structure

Let's start by creating a new file with a .sh extension. As an example, we could create a file called devdojo.sh.

To create that file, you can use the touch command:

touch devdojo.sh

Or you can use your text editor instead:

nano devdojo.sh

In order to execute/run a bash script file with the bash shell interpreter, the first line of a script file must indicate the absolute path to the bash executable:

#!/bin/bash

This is also called a Shebang.

All that the shebang does is to instruct the operating system to run the script with the /bin/bash executable.

However, bash is not always in /bin/bash directory, particularly on non-Linux systems or due to installation as an optional package. Thus, you may want to use:

#!/usr/bin/env bash

It searches for bash executable in directories, listed in PATH environmental variable.