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.

dockerbash.tar.gz

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

# How Important is this Lesson?

If you write, use or maintain bash of any complexity you'll want to
know how to debug it!

# Syntax Checking Options 

Start by creating this simple (but broken) script:

cat > debug_script.sh << 'END'
#!/bin/bash
A=some value
echo "${A}
echo "${B}"
END

Now run it with the `-n` flag. This flag only parses the script, rather than
running it. It’s useful for detecting basic syntax errors.

You can see it’s broken. Fix it. Then run it:

You'll see:

```html
    [1]+  Done                    sleep 60
```

in the terminal.

Again, it reports the job number, this time with the status (`Done`), and the command
that was originally run (`sleep 60`).

# Controlling Jobs

Just like starting jobs, you can control jobs by sending signals to them.

Here you're going to start two jobs, one to sleep for two minutes, and the next for one
second more (so we can distinguish between them).

Try tracing to see more details about what’s going on. Each statement gets a new line.


Using these flags together can help debug scripts where there is an elementary
error, or even just working out what’s going on when a script runs. I used it
only yesterday to figure out why a systemctl service wasn’t running or logging.

Fix the error you see before continuing.

# Managing Variables

Variables are a core part of most serious bash scripts (and even one-liners!),
so managing them is another important way to reduce the possibility of your
script breaking.

Change your script to add the ‘set’ line immediately after the first line and
see what happens.

```
#!/bin/bash
set -o nounset
A="some value"
echo "${A}"
echo "${B}"
```

In this lesson, you will learn about bash flags useful for debugging, how to trace bash code, and useful resources for linting bash scripts.

Core Bash

Scripting Bash

Bash in Practice

Advanced Bash

Debugging

How Important is this Lesson?

Syntax Checking Options

Controlling Jobs