Mastering the Linux Terminal / Command-Line

Nihey Takizawa — Mon, 08 Apr 2024 14:37:35 +0000

Using the terminal is something any developer will eventually need. It is part of my daily routine to perform almost all of my development activities in a terminal, mastering this skill is something that will certainly boost your productivity and make you learn how to use any command-line interface (CLI) faster.

How to read a Manual

When you wish to read the manual or help section of any command-line, it is pretty straightforward, just run: man <command> or <command> --help and it should give you some instructions on how to do it, right? But do you know how to read these manuals properly?

For instance, by running:

man git

It will give you this man page.

You can navigate it by using the arrow keys and quit using q

Do you understand what this section means with its symbols and conventions?

git [-v | --version] [-h | --help] [-C <path>] [-c <name>=<value>]
    [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
    [-p|--paginate|-P|--no-pager] [--no-replace-objects] [--bare]
    [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]
    [--super-prefix=<path>] [--config-env=<name>=<envvar>]
    <command> [<args>]

Alternatives

Let's analyze the part:

git [-v | --version]

The pipe (|) character means that you can use one option or the other. This can mean that both option would either be mutually exclusive (or would not make sense)

Optional and Required Arguments

The brackets inside the brackets ([]) means the argument is optional, so you are not required to insert any of them unless you want to explicitly use them.

git [-v | --version] [...] <command> [<args>]
      │                │                │
      │                │                │
      └────────────────┴────────────────┴─ All Optional

Arguments inside lesser and greater than symbols <> are always required.

git [-v | --version] [...] <command> [<args>]
                               │
                               │
                            Required

This shows us that the only mandatory argument when using the git command is an argument named <command> that should be positioned before all of these optional arguments, and after this, there are some optional arguments that can be set after it.

# Simplified documentation
git <command> [<args>]

Conventions

There are some argument conventions that most command-line utilities use and can make your life easier when understanding command-line usage.

Short Options

Several command-line offer short options for common used arguments, for instance the ls command:

-a, --all
       do not ignore entries starting with.
-l     use a long listing format
-h, --human-readable
       with -l and -s, print sizes like 1K 234M 2G etc.

The short options are usually prefixed by a single hyphen (-) (e.g.: -a), long options are usually prefixed by double hyphen -- (e.g.: --all).

Combining arguments

Some command-line software support combining short options by simply putting everything together, for instance, these two commands produce the same output:

ls -lah
ls -l -a -h

Arguments with Parameters

Some command-line software support arguments with parameters, one common convention is to be able to use both of them indicated by space or by = sign.

# These are the same
git commit -a --author="Name <email@email.com>"
git commit -a --author "Name <email@email.com>"

Sometimes a parameter can appear immediately after the option:

grep "Text to Find" * -R -n2
                          │
                          └─ Shows two lines before and after the found text

Navigating the man pages

When navigating the manual or help pages or a particular command, it is common that they are presented in the less command, in which you can navigate the manual using the arrow up and down keyboard keys.

But you can also navigate it using:

Page Up -> Navigate one page (screen size) up
Page Down -> Navigate one page (screen size) down
Home -> Go to the beginning
Down -> Go to the end

You can also perform search with: /<pattern>, and it will search for the pattern you've typed.

After searching you can navigate by using:

n -> Go to the next result
N -> Go to the previous result

If you wish to learn more about less, you can check:

man less

Also, now you can finally RTFM

DEV Community: Nihey Takizawa