Introduction To Linux

About Linux

Linux is a free, open-source operating system kernel developed by finish software engineer named Linus Torvalds in 1991 as his 

Linux has been under active development since 1991. It has evolved to be versatile and is used all over the world, from web servers to cellphones.

However, newcomers to Linux may find it difficult to approach the structure of an unfamiliar operating system.

This guide gently introduces key terminal skills and equips newcomers to learn more about Linux.

The Terminal

For most of the time you access a cloud server, you'll be doing it through a terminal shell. The shell allows you to execute commands on the droplet.

All administrative tasks can be accomplished through the terminal. This includes file manipulation, package installation, and user management.

The terminal is interactive. You specify commands to run. The terminal outputs the results of those commands. Executing any command is done by typing it and pressing Enter.

Navigation

Linux filesystems are based on a directory tree. This means that you can create directories (or "folders") inside other directories, and files can exist in any directory.

To see what directory you are currently active in:

pwd

This stands for "print working directory", and will print the path to your current directory. The output can look similar to this:

/home/foo

This means that your current active directory is foo, which is inside home, which lives in the root directory, /.

To see other files and directories that exist in your current working directory:

ls

This will give you a list of names of files and directories. To navigate into a directory, use its name:

cd <name of directory>

This will change your new current working directory to the directory you specified. You can see this with pwd.

Additionally, you can specify .. to change to the directory one level up in your path. To get back to your original directory:

cd ..

We can also create new directories in our current working directory. For example, to create a new directory called bar:

mkdir bar

Then we can

cd

into bar if we want. We can also delete bar if we no longer find it useful:

rm -d bar

rm -d

will only delete empty directories.

File Manipulation

Files cannot be used with

cd

(it stands for "change directory").

Instead, we can view files. Say we have a file baz in our current directory:

cat baz

This will print out the entire contents of baz to the terminal.

With long files, this is impractical and unreadable. To paginate the output:

less baz

This will also print the contents of baz, but one terminal page at a time, beginning at the start of the file.

Use the spacebar to advance a page, or the arrow keys to go up and down one line at a time. Press q to quit out of less.

To create a new file called foobar:

touch foobar

This creates an empty file with the name foobar in your current working directory. The contents of this file are empty.

If we decide foobar isn't such a good name after all, we can rename foobar to fizzbuzz:

mv foobar fizzbuzz

mv

stands for "move" and it can move a file or directory from one place to another.

By specifying the original file, we can "move" it to a new location in the current working directory, thereby renaming it.

It is also possible to copy a file to a new location. If we want to bring back foobar, but keep fizzbuzz too:

cp fizzbuzz foobar

Just as you guessed,

cp

is short for "copy". By copying fizzbuzz to a new file called foobar, we have replicated the original file in a new file with a different name.

However, what good is a file if it contains nothing? To edit files, a file editor is necessary.

There are many options for file editors, all created by professionals for daily use. Such editors include vim, emacs, nano, and pico.

nano is a perfectly suitable option for beginners. It is easy and simple to use, with no bells or whistles to confuse the average user.

To edit text into foobar:

nano foobar

This will open up a space where you can immediately start typing to edit foobar.

To save the written text, press

Ctrl-X

then y. This returns you to the shell with a newly saved foobar file.

Now foobar has some text to view when using

cat

or

less

.

Finally, to delete the empty fizzbuzz:

rm fizzbuzz

Unlike directories, files are deleted whether they contain content or not.

The Filesystem Hierarchy Standard

Nearly all Linux distributions are compliant with a universal standard for filesystem directory structure.

The FHS defines clearly determined directores for different purposes.

The symbol / is used to indicate the root directory in the filesystem hierarchy defined by the FHS.

When a user logs in to the shell, they'll be brought to their own user directory in /home.

The FHS defines /home as containing the home directories for regular users. (root has its own home directory in /root, also specified by the FHS.)

Because default, common-sense locations are provided for many different kinds of files, organisation of files for different purposes is simplified.

Permissions

On a system with multiple user accounts, determining who is allowed to interact with what files is important.

Linux supports unix-style filesystem permissions, which restricts who can read and write certain files.

Permissions are an expansive and profound topic, discussed in detail in our permissions article.

A Culture of Learning

So far, this guide only serves to teach the basics of toddling around in a Linux environment. But finding your way around the Linux environment requires dedication and a curious mindset.

When you have a question about how to accomplish a task, there are several avenues of instruction you can turn to.

First and foremost, Google and DuckDuckGo are invaluable resources. Odds are that if you have a question, many others have already asked it and had the question answered.

Your immediate instinct should be to look for the answer through those search engines.

When your question has to do with any Linux command, the manual pages offer detailed and insightful documentation for nearly every single command.

To see the man-pages for any command:

man <command>

For instance,

man rm

displays the purpose of rm, how to use it, what options are available, examples of use, and more useful information.

Gaining the information you seek is an essential skill, which will sustain your Linux career for as long as you stay devoted to a time of learning.

·                                                                                                                            Justin Kim

                                                                                                                 source: digitalocean