Mislav Jurić

Tag: Linux Tutorial

  • Linux Tutorial Series – 14 – Starting a shell session

    Here is the video version, if you prefer it:

    To start a shell session, find Terminal on your Linux distribution (via the graphical user interface) and click on it. That should start a shell session, which means you can type in commands!

    We will be writing some commands in the very next article, so stay tuned!

  • Linux Tutorial Series – 13 – What is a command?

    Here is a video version, if you prefer it:

    This may be a very simple question – what is a command? What is a command in the context of the Linux shell environment?

    Commands are, in essence, running a program with options and arguments. (Barrett, 2016)⁠ If you write, for example, ls -l file.txt, you are calling a program called ls with the option -l and the argument file.txt. But wait a minute – how does the operating system know where to find the ls program? This is not the focus of this article so we don’t currently care. As far as we are right now concerned, the operating system “does its magic” so it can find the program ls and call it with the specified options.

    There are a lot of things you can do with commands – commands can be piped, meaning output of one command is input to another and there can exist scripts which within themselves contain lots of commands. But again, essentially, a command is just a single program, with its options and arguments.

    Hope you found this useful!

    References

    Barrett, D. J. (2016). Linux pocket guide (3rd ed.). O’Reilly Media. Pages 3-4

  • Linux Tutorial Series – 12 – What is a shell?

    Here is the video version, if you prefer it:

    The shell, the shell… We all heard that. We know you can type some command in the shell in a Linux environment and get some output. But what does the shell actually mean?

    “A shell is a program that runs commands”, says (Ward, 2014)⁠. That is basically it. You type some commands in, the shell executes them, then you get some output. Shell scripts, another popular term, are essentially just commands typed in a file called a shell script; so the shell has the same job – execute commands.

    There are multiple kinds of shells. You can find more information here: (“5 Most Frequently Used Open Source Shells for Linux,” n.d.)

    Before I end, it is important to note that programs like Terminal are not actually shells – they are graphical user interfaces running shell on your behalf. (Barrett, 2016)⁠ Figure 1 depicts this. This program with a graphical user interface, called a terminal emulator, interacts with the shell. (Shotts, 2019)⁠

    Figure 1 – Relationship between graphical user interfaces to the shell and the shell itself (modeled after figure on page 15 of (Barrett, 2016)⁠)

    Hope you learned something new!

    References

    5 Most Frequently Used Open Source Shells for Linux. (n.d.). Retrieved December 22, 2019, from https://www.tecmint.com/different-types-of-linux-shells/

    Barrett, D. J. (2016). Linux pocket guide (3rd ed.). O’Reilly Media. Page 15

    Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Page 26

    Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Page 12

  • Linux Tutorial Series – 11 – Checkpoint

    Here is the video version, if you prefer it:

    In the following section of the posts, we will talk about some really foundational things, such as what is a shell, what is a command, what are absolute and what are relative paths and so on.

    All of the conceptual things covered here will be of crucial importance later on, so it pays to pay attention.

    Talk soon!

  • Linux Tutorial Series – 10 – Recap

    Here is the video version, if you prefer it:

    We have talked about what an operating system is – it is a very useful piece of software which enables you to communicate with the hardware conveniently. We also talked about the kernel and learned that it manages processes, memory, device drivers and system calls, as well as established that users are people that use the computer and each one has (or should have) a user account associated with him/her.

    We established that there is a difference between the user space and the kernel space, as well as there being a difference between regular users and superusers. Kernel space is only accessible to the operating system, while the user space is where the user programs reside. Superusers get to execute certain commands that regular users can’t (don’t have the permission to). We learned that a Linux distribution is an operating system made from a software collection that is based upon the Linux kernel.We also talked about some Linux installation details.

    Hope this served as a good review!

  • Linux Tutorial Series – 9 – Installing Linux

    Here is the video version, if you prefer it:

    In this article, I will explain how to install Linux on your machine. I will assume you are installing Debian (Debian 9 to be specific), but most likely any Linux distribution will have a similar installation process. If not, there is a website called Google, through which you can find guides that guide you through the specifics of your installation.

    When I installed Debian on my PC, I pretty much just clicked “Next” all the time. I used the default settings. Nothing fancy. The only setting up I had to do was when I was creating my partitions. Partitions are subdivisions of your hard disk drive or your solid state drive. Partitions enable you, so to speak, divide up your disk into different compartments. We will talk more about this later on, but a guide I used for this (and you can use for this) is (Trivedi, n.d.).

    There is also one thing I was uncertain about, which is swap. Swap is a part of your hard disk drive (and when I say hard disk drive, I mean solid state drive as well, if you have one) that you can use if you run out of Random Access Memory (RAM). So for example, if I have 8 Gigabytes (GB) of RAM⁠, and if I need 9 GB to run all my processes (since all processes reside in RAM) I need 1 additional GB of RAM. That additional 1 GB gets taken from the swap space. Swap space is also used when you hibernate your computer. (“SwapFaq,” n.d.)⁠ I found a really good guideline for swap space here – (“I have 16GB RAM. Do I need 32GB swap?,” n.d.). The second answer from the top contains a nice table. There are other guides on this website called Google, feel free to use them, but in general I think that if your swap is at least the size of your RAM, that’s going to be fine.

    A note: You can also install Linux on a virtual machine and learn how to use Linux via a virtual machine, or maybe you can have a dual boot with both Windows and Linux and slowly switch over to Linux. I personally found those approaches to be less effective. The reason was that I would keep using Windows over Linux, even though I knew I should use Linux. Maybe for you this will work, so I am mentioning it here.

    A Google search for “How to set up Linux on VirtualBox” (VirtualBox is used for virtualization) can help you set that up.

    Hope this helped!

    References

    I have 16GB RAM. Do I need 32GB swap? (n.d.). Retrieved December 22, 2019, from https://askubuntu.com/questions/49109/i-have-16gb-ram-do-i-need-32gb-swap

    SwapFaq. (n.d.). Retrieved December 22, 2019, from https://help.ubuntu.com/community/SwapFaq

    Trivedi, Y. (n.d.). How to Choose a Partition Scheme for Your Linux PC. Retrieved December 22, 2019, from https://www.howtogeek.com/howto/35676/how-to-choose-a-partition-scheme-for-your-linux-pc/

  • Linux Tutorial Series – 8 – Linux distribution

    Here is the video version, if you prefer it:

    I wanted to clarify a term, which is Linux distribution. Linux distribution is an operating system made from a software collection that is based upon the Linux kernel. (“Linux distribution,” n.d.)

    What does that mean? That means that all Linux distributions have the same kernel (which, as we discussed, is the central part of the Linux operating system)⁠, but they differ in the software which comes supplied with them.

    Which Linux distribution should you pick? I can only recommend what I used so far – either Ubuntu or Debian. There are a lot of others, so feel free to pick the one you like. I prefer Debian over Ubuntu, but again, feel free to pick the one you like.

    Hope you learned something useful!

    References

    Linux distribution. (n.d.). Retrieved February 29, 2020, from https://en.wikipedia.org/wiki/Linux_distribution

  • Linux Tutorial Series – 7 – Superuser and a regular user – what is the difference?

    Here is the video version, if you prefer it:

    What is the difference between the superuser and the regular user? The superuser (also known as root) has some extra privileges on the Linux system. (Ward, 2014)⁠ For example, if you are a regular user and you try to modify some system files, you will most likely not be able to save them and get “Permission denied” error. That’s because system files are only accessible by the superuser.

    So the superuser is the most powerful user on the Linux system. Other users aren’t as powerful (meaning they can’t modify some files and can’t execute some commands). But guess what – that is good. “How can that be good?”, you might wonder. Well, imagine you downloaded a malicious piece of software that tried to modify your system files and you are logged in as a regular user. When the malicious piece of software tries to modify some system files, it can’t, because a regular user can’t modify them, you are running the program as a regular user and thus the malicious program can’t modify the files. I am not an expert in information security, but I remember this example being tossed around in some of my college classes, so I decided to put this in.

    Hope this helped clarify the difference between the superuser and other users.

    References

    Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 9-10

  • Linux Tutorial Series – 6 – User space and system space – what is the difference?

    Here is the video version, if you prefer it:

    User space is the space that “normal” processes use. System space (aka kernel space) is the space that only the operating system can use. ⁠

    See, every program has to be stored in random access memory (RAM). That means that the operating system also has to be stored in RAM. (Ward, 2014)⁠ So the operating system uses the RAM, user programs (your normal every day programs such as Mozilla Firefox) use the RAM, everyone uses the RAM! Now, the thing about the operating system is, because of security reasons and because of potential issues, it limits the user processes to a part of RAM called user space and the operating system resides in a different part of the RAM. If any process (process being another word for a program you have started on your computer) tries to access any part of the memory which is not its own, it can’t. The operating system makes sure of it. The figure below should help clarify things.

    Figure 1 – System and user space (my own illustration)

    Hope you learned something useful!

    References

    Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 8-9

  • Linux Tutorial Series – 5 – Users

    Here is the video version, if you prefer it:

    This quick post serves one purpose – to tell you that users are the people who use the computer. More specifically, every user has (or at least should have) a user account associated with him/her. That means that multiple people can use the computer and it is desirable that each one of them has their own user account, because Linux makes sure that users can’t access each others stuff.

    Thank you for reading!