migrated all posts from 2018

1 files changed, 299 insertions, 0 deletions

diff --git a/content/weblog/2018-11-05_intro-to-linux-and-bash/index.md b/content/weblog/2018-11-05_intro-to-linux-and-bash/index.md
new file mode 100644
index 0000000..28db692
--- /dev/null
+++ b/content/weblog/2018-11-05_intro-to-linux-and-bash/index.md
@@ -0,0 +1,299 @@
++++
+title = "Intro to Linux and the Bash command line"
+date = 2018-11-05T23:53:00Z
++++
+
+Recently I decided to introduce a friend of mine to the wonderful world of
+Linux, and like when someone moves to a completely new town, you have to help
+that friend get around town and learn about how things work in this new town,
+where are all the places of interest, etc. And so it is, in someway, when
+someone decides to make the move to a new OS, they have to get used to the new
+environment and make new habits, especially regarding Linux. Therefore, I
+decided to write this tutorial for my friend, and anybody who decided to try
+Linux, and want to learn to use more effectively, that is, with a higher level
+of skill than an average user.
+
+<!-- more -->
+
+Most probably you already know, but Linux is not actually the OS itself, but
+rather the kernel that is used in conjuction with a collection of programs and
+packages called GNU (insert here jokes and memes about GNU/Linux (or
+GNU+Linux)), and there are many different distributions (over 9000) of said
+GNU/Linux.
+
+If you're just about to install Linux, and haven't decided yet on a distro, here
+I wrote a small list of distros that might start with:
+
+* Manjaro - I personally use this distro. This one has different releases, with
+  different Desktop Environments (or DEs), like KDE or GNOME. This is a "rolling
+  release", what that means, is that instead of the classical update to version
+  x.x of the OS system, updates for each package are being rolled out
+  constantly, and sepparatly for each package. That is, you get basically the
+  latest packages, with the latest updates, at the cost of maybe some stability.
+  It is quite easy to get installed, and get started with (If you choose an
+  official release like Manjaro KDE or Manjaro GNOME).
+* Ubuntu - The most know Linux distribution. It is one of the most
+  "user-friendly" distros out there. It is more stable than Manjaro (although
+  not always, unless you're using the Long-Term Support versions). If you just
+  want to install an OS where everything just works, and is already configured
+  for you, and you don't want to choose from a list of DEs (or you don't know
+  what a Desktop Environment is), this will most probably suit your needs.
+* Debian - One the most stable distributions. It is not as easy to install as
+  Ubuntu or Manjaro due to large ammount of choice given during installation,
+  but it's not really hard to either. Actually, Ubuntu is derived from Debian.
+  You must probably will have to configure it to your needs and likings
+  (personally, I dislike the default settings of GNOME), but if you want real
+  stability, and distro that has been around almost as long as the kernel
+  itself, then this might be the distro for you. One downside of Debian, is that
+  because of its focus on stability, many packages on the main (stable)
+  branch/version are quite old/outdated. Another con of Debian, is that it
+  doesn't include "non-free" packages in the main repository (that is, there are
+  no proprietary packages by default), so if need a proprietary program or
+  package, like nvidia's drivers, you will have to add the corresponding
+  repositories by yourself.
+* Fedora - It is similar to Ubuntu regarding stability and ease of use (i.e.
+  quite simple to use). I can't say much about Fedora, because I haven't used it
+  that much myself, but it is a very popular distribution. It has the same con
+  as Debian, in that it doesn't include "non-free" software in its main
+  repository.
+
+If you found "Desktop Environment" to be a unfamiliar term, in a nutshell, it is
+the collection of programs and packages that present with the Graphical User
+Interface for interaction with the system. How your OS/distribution is going to
+look like doesn't depend as much on the distro itself, as on the DE that you
+choose to install or comes with the distro.
+
+Do you have Linux installed? Excellent, now we can get started.
+
+## File structure
+
+If you are used to working with Windows systems, the the first thing that you
+might notice is the difference in how files are handled/organized. In Windows,
+because of its DOS legacy, drive letters are used to represent different drives,
+partitions and file systems. In Linux, like in other Unix-like systems (e.g.
+macOS, BSD) this differs somewhat.
+
+In Linux, everything is a file, including the devices that are connected to your
+computer. From your keyboard (which is a read-only file) to your drives.
+Directories are also files.
+
+Different disks or drives are mounted in a specific directory, and from this
+directory, every file from that drive will be accessible. You can mount and
+unmount drives yourself, but if you installed a distro with any of the most
+popular desktop environments, then there's nothing to worry about, the system is
+going to take care of mounting your pendrive for you, and creating a shortcut in
+your file explorer and/or desktop each time you insert it.
+
+Linux has what is called a "root" directory
+
+```
+/
+```
+
+In there are the files and subdirectories in your system are located, including
+drives mounted in a specific subdirectory as mentioned before.
+
+Each user in Linux has its own "home" directory. Inside your home directory your
+personal documents/files and subdirectories are going to be stored. All the home
+directories of each user are usually going to be stored inside the "/home/"
+directory. For example, for user "user", their home directory is going to be
+
+```
+/home/user
+```
+
+However, you can also move to your home directory by using the symbol ~. For
+example, in your terminal, if you input
+
+```sh
+$ cd ~
+```
+
+You are going to be taken to your home directory (e.g. "/home/user/").
+
+## The command-line - Bash
+
+Arguably the most useful program in Linux and any *nix system is the terminal.
+Yes, maybe the average user won't have to use it, but it is the most flexible,
+effective and useful instrument in your computer. A lot of work can be done
+faster and more effectively in the terminal, rather than in a GUI. Obviously, it
+is faster to learn to use a graphical interface, than a text-based or
+command-line one, however, once you learn to properly use the terminal, you will
+be able to use computer more efficiently than ever.
+
+Your command-line, if you haven't changed any defaults, will most probably look
+something like this
+
+```sh
+user@host:~$
+```
+
+The first part before the "@" symbol, is the user with whom you have logged in.
+After the "@" symbol is the "hostname" of your machine, i.e. the name of your
+computer in a network.
+
+After the semicolon ":", the directory in which you are currently located is
+going to be displayed. In our case, the "~" symbol is displayed, meaning that we
+are inside our home directory. If you wish to see the full absolute path in
+which you are located, you can input the command "pwd"
+
+```sh
+user@host:~$ pwd
+/home/user
+user@host:~$
+```
+
+The dollar "$" symbol, tells us that we are logged in as "normal" user. In Linux
+and all *nix systems, there is a so called "super user", or just the "root" user
+for short. Normal users don't have full access to all of the files in the
+system, including other users' files. The root user has full access to all
+system files. When you are logged in as the root user, the dollar "$" symbol is
+going to be replaced by the hash "#" symbol.
+
+However, we will be talking about the root user and permissions another time.
+
+I can't tell you exactly how to open the terminal, as it is different in each
+distro and desktop environment. You will have to look for the link that says
+"Terminal" in your programs' menu, with the icon of a terminal on it.
+
+To be able to start working in the terminal, we'll need to become acquainted
+with some of the main commands used for navigating.
+
+### Navigation in the terminal
+
+There is one more thing that needs to be taken into consideration when working
+with Linux and Unix-like systems, and that is, case-sensitivity. *nix systems
+are case-sensitive, in contrast to Windows ones, which aren't. What that means,
+is that, if on Windows, files "README.TXT" and "readme.txt" are the same file,
+in Linux and Unix they are completely different files.
+
+To move around directories, we use the "cd" (or change directory) command,
+followed by the name, or path of the directory. The directory can be absolute or
+relative.
+
+A relative path, is, for example, the name of a subdirectory inside the
+directory in which we are currently located. In other words, the path relative
+to where we are located.
+
+An absolute path, is the path relative to the root directory.
+
+For example, if we want to move to the "Documents" directory inside
+"/home/user/", and we are already at "/home/user/", the we can just type the
+following
+
+```sh
+user@host:~$ cd Documents
+user@host:~/Documents$
+```
+
+If we wanted to move to that same directory from another location in the system,
+we would type
+
+```sh
+user@host:/var$ cd /home/user/Documents
+user@host:~/Documents$
+```
+
+To move one folder up, we write "..". Example
+
+```sh
+user@host:~/Documents$ cd ..
+user@host:~$
+```
+
+The two dots "..", means the root directory of the current subdirectory. One dot
+"." means the current directory.
+
+There is one more command, that will aid you in navigating - ls. This command
+outputs a list of files and directories in the current location
+
+```sh
+user@host:~/Documents$ ls
+Books       todo.txt    picture.png
+```
+
+This command also accepts arguments and flags. For example, to list hidden files
+as well, add the "-a" flag
+
+```sh
+user@host:~/Documents$ ls -a
+Books    .secret    todo.txt    picture.png
+```
+
+Hidden files in Linux start with a dot (e.g., hidden directory ".secret").
+
+There is also the "-l" parameter, which shows us a list of the contents with
+additional information, such as, permissions (more on that in the next part),
+amount of files inside a directory, owner of the file (user and group), size on
+disk, datetime of creation/modification, and the name of the file. Example
+
+```sh
+user@host:~/Documents$ ls -l
+drwxr-xr-x  2 user user 4.0K Jul  18 04:20 Books
+-rw-r--r--  1 user user 350  Jul  18 04:20 todo.txt
+-rw-r--r--  1 user user 1.2M Jul  18 04:20 picture.png
+```
+
+You can mix flags as well,
+
+```sh
+user@host:~/Documents$ ls -al
+drwxr-xr-x  2 user user 4.0K Jul  18 04:20 Books
+drwxr-xr-x  5 user user 4.0K Jul  18 04:20 .secret
+-rw-r--r--  1 user user 350  Jul  18 04:20 todo.txt
+-rw-r--r--  1 user user 1.2M Jul  18 04:20 picture.png
+```
+
+You can also take a look at what is inside a directory without having to move to
+it first, by passing along as the last argument the name/path of said directory,
+for example
+
+```sh
+user@host:~/Documents$ ls -l Books
+drwxr-xr-x 12 user user 4.0K Jul  18 04:20 Lessons
+-rw-r--r--  1 user user 2.3M Jul  18 04:20 Crime and Punishment.pdf
+```
+
+### Shortcuts
+
+Before we conclude the first part of this tutorial, I would like to mention some
+useful "shortcuts" in bash.
+
+The first one is command history. Each time you input a command into the
+terminal, it saves it in a history file. You can move around your command
+history by using the up and down arrows. Let's say you want to repeat the last
+command you used, instead of typing it all over again, you could just hit the up
+arrow one time, maybe modify it a bit, and then press enter to input it. If you
+want to use an older command, you can press the up arrow multiple times, and if
+you missed the command you needed, you can go forward in your history by
+pressing the down arrow.
+
+There is one more useful thing in Bash - Tab completion. When you press the
+"Tab" key, bash will try to autocomplete the command for you.
+
+Let's say, for example, that you are in the root directory and you want to move
+to "/home/user/". you can start typing "cd h", then press "Tab", so you now have
+"cd home/", now type "u", press "Tab" one more time, and now you have "cd
+home/user/".
+
+If there are multiple possible options to be autocompleted, then on the first
+hit of the "Tab" key you are not going to get anything. If you don't get
+anything it could also mean that there are nothing to autocomplete. In the first
+case, if you press "Tab" twice, bash is going to output a list of possibilities,
+for example
+
+```sh
+user@host:~$ cd Do
+Documents/ Downloads/
+user@host:~$ cd Do
+```
+
+In this case, we can type the next letter, for example "cd Doc", and press "Tab"
+one more time, and we are going to get "cd Documents/". However, if you didn't
+get anything on pressing "Tab" twice, it means that is nothing to autocomplete.
+
+It can be a little be hard to understand at first how "Tab completion" works,
+but the best way to understand it, by trying it yourself.
+
+That is all for now, in the next part I am going to talk more about working on
+the terminal.