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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tset

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

**Readline** is one of those technologies that is so commonly used people don't realise it's there. In this lesson I want to make you aware of it and introduce some concepts and examples of its use so you're able to deal with any problems that arise from its use or misuse.


# How Important is this Lesson? 

Writing bash does not require a knowledge of readline. Understanding
readline helps greatly to understand what is going on at the terminal
and at the command line.

# Bash Without Readline

First you're going to see what bash looks like without readline.

In your 'normal' bash shell, hit the `TAB` key twice. You should see
something like this:

```html
Display all 2335 possibilities? (y or n)
```

That's because bash normally has an *autocomplete* function that allows
you to see what commands are available to you if you tap `TAB` twice.

Hit `n` to get out of that autocomplete.

Similarly, if you hit the up arrow key a few times, then the previously-run
commands should be brought back to the command line.

Now type:


The `--noediting` flag starts up bash without the readline library enabled.
If you hit tab twice now you will see something different: the shell no
longer 'sees' your tab and just sends a tab direct to the screen. Autocomplete
has gone.

Autocomplete is just one of the things that the readline library gives you in
the terminal. You might want to try hitting the up or down arrows as you
did above to see that that no longer works as well.

Hit return to get a fresh command line, and exit your non-readline-enabled
bash shell:

# Other Shortcuts

There are a great many shortcuts like autocomplete available to you if readline
is enabled. I'll quickly outline four of the most commonly-used of these before
explaining how you can find out more.


There should not be many surprises there. Now:

- If you hit the `up` arrow, you will see
you can get the last command back on your line

-  If you like, you can re-run the
command, but there are other things you can do with readline before you hit
return

- If you hold down the `ctrl` key and then hit `a` at the same time your cursor will
return to the start of the line
- Another way of representing this 'multi-key' way of inputting is to write it like this: `\C-a`. The `\C` represents the control key, and the '`-a`'
represents that the `a` key is depressed at the same time

- Now if you hit `\C-e` (`ctrl` and `e`) then your cursor has moved to the end of the
line. I use these two shortcuts dozens of times a day

- Another frequently useful one is `\C-l`, which clears the screen, but leaves your
command line intact

- The last one I'll show you allows you to search your history to find matching
commands while you type. Hit `\C-r`, and then type `ec`. You should see the
`echo` command you just ran like this:


```html
(reverse-i-search)`ec': echo echo
```

- Then do it again, but keep hitting `\C-r` over and over

- You should see all the
commands that have `ec` in them that you've input before (if you've only got one
`echo` command in your history then you will only see one)
- As you see them you are
placed at that point in your history and you can move up and down from there or
just hit return to re-run if you want

Here's a table of the most frequently used shortcuts for reference:

|  Readling Shortcut   |  Effect   |
| --- | --- |
|  \C-a   |  Takes you to start of line   |
|  \C-e   |  Takes you to end of line   |
|  \C-h   |  Delete character   |
|  \C-l   |  Clear screen   |
|  \C-r   |  Review history   |


> Note: What is your **history**? Your history is a list of commands that were previously-ran in your shell. We will cover this in a [later lesson](https://www.educative.io/courses/master-the-bash-shell/bash-history).

There are many more shortcuts that you can use that readline gives you. Next
I'll show you how to view these.

# Using `bind` to Show Readline Shortcuts

If you type:

In this lesson, you’ll learn about what readline is, what bash looks like without it, and how to manipulate and find out more about its features.

Core Bash

Scripting Bash

Bash in Practice

Advanced Bash

The Readline Library

How Important is this Lesson?

Bash Without Readline