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Another nice feature of the
bash shell is command line completion.

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You can use the tab key for command
line completion and this works on different items.

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It works for commands, for variables,
and for file names as well.

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If you install the bash completion package,
you even have some additional completion features.

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You should know that this bash
completion package in many cases is already

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installed. Let me show you how
awesome this command line completion is.

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Let me start by using sudo user and
then I'm pressing tab. What is happening? Nothing.

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There's a good reason that nothing is happening, because when
you press tab, then the bash shell is trying to complete.

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But if there's multiple options, it doesn't show you anything.
You need to press the tab key twice and aha. There

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I can see there's a handful of commands that
are starting with user When I use sudo user helper.

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I have no idea what it is by the way, but I'm
just pressing the h and then I'm pressing tab again and it completes.

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Let's use help and aha. It
doesn't have the valid option. That doesn't

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matter. This is not about user
helper, this is about bash completion.

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Now another one is on variables.
I'm going to use Echo $his

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and pressing tab and that's showing
historical tab tab and that is

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showing his size. Well, that's convenient.
What do we have in there?

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We have a
value of 1,000.

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That's the total size of my
bash history. But the thing here is

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we have these variables and you
can use completion on variables as well.

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It also works
on file names.

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If ever you create a crazy long file
name, don't worry, you don't have to type

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the entire file name. If you want to
remove it, just use RM followed by enough

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to uniquely identify the file name and press
the tab key. Then it will be removed.

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But probably the most
powerful feature is within commands.

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Let's use sudo IP tab Tab
IP is the command that allows

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you to do stuff with your
IP addresses. I'm making that IP

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addr tab tab that should
be IP address tab tab.

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That's showing all the commands
that are available. Well, let's just

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use IP address show to
show the current IP addresses.

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Now the nice thing about these complex commands
is that from the bash completion package, you install

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additional information on how to complete these complex
commands. That means that you don't need to use

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help or man pages or whatsoever. You
just display everything on screen using tab completion.