Gain insights into the intricacies of the Bash shell, ideal for beginners. Delve into essential skills with interactive learning designed to ensure lasting knowledge without requiring prior experience.

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A course for anyone interested in understanding all aspects of the bash shell. Designed for use by beginners, it assumes as little knowledge as possible but teaches you all the intricacies of bash it took me decades to learn by trial and error. 

The interactive nature of the course instills the knowledge in a way you will not forget!

Master the Bash Shell

From one angle, bash can be viewed as a programming language, albeit a quite
slow and primitive one.

One of the language features it has is the capability to create and call
*functions*.

This leads us onto the topic of what a ‘command’ can be in bash, and we cover all four of them: *functions*, *aliases*, *programs*, and *builtins*.

By the end you will have a more nuanced understanding of commands in bash.

# How Important is this Lesson?

It's possible to get by without knowing much about functions in bash,
but any serious bash user will know what they do and how they work.


# Basic Functions

Start by creating a simple function:

function myfunc {
    echo Hello World
}
myfunc

> Note: continue to use this terminal during this lesson. Throughout this course it is assumed that you complete each lesson by typing in the commands in the provided terminal for that lesson in the order the commands are given.

By declaring a function, and placing the block of code that needs to run inside the
curly braces, you can call that function on the command line as though it
were a program.

# Arguments

Unlike other languages, in bash there is no checking of functions' arguments.

Predict the output of this, and then run it:

function myfunc {
    echo $1
    echo $2
}
myfunc "Hello World"
myfunc Hello World

Can you explain the output? If not, you may want to re-read the previous lessons!

Arguments to functions are numbered, from **1 to n**. It’s up to the function to
manage these arguments.

In the above example, in **line 5**, the quotes turn the `Hello World` string into a single argument, which is echoed on a single line. It is then followed by an empty line, because there was no second argument provided. In **line 6**, the `Hello World` string is not enclosed in quotes, so is treated as two separate variables, which are `echo`ed on two separate lines as two separate arguments.

This illustrates a very important point about shells, which is that they separate items by space by default. This will become very important when we discuss the `IFS` in a [later lesson](https://www.educative.io/courses/master-the-bash-shell/the-internal-field-separator)

# Variable Scope

Variables can have scope in bash. This is particularly useful in functions,
where you don’t want your variables to be accessible from outside the function.

These commands illustrate this:

This lesson discusses the four types of a ‘command’ that exist in bash: functions, aliases, programs, and built-ins.



Core Bash

Scripting Bash

Bash in Practice

Advanced Bash

Functions

How Important is this Lesson?

Basic Functions

Arguments