Tag: command

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Linux Tutorial Series

Linux Tutorial Series – 19 – Directories and files

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In Linux, you will find both directories and files. Think of directories like folders in Windows or like drawers or folders in everyday life – they are used to store files within them and give structure to your files. (“Directory (computing),” n.d.)⁠ Files are resources for storing information. (“Computer file,” n.d.)⁠

Directories also have a hierarchy. So we can have directory1/directory2. That means that directory2 is a child directory of directory1. Imagine this as a folder within a folder. When we list the “hierarchical trajectory” from some directory to some other directory, we are talking about a path. (“Path (computing),” n.d.)⁠

Hope you learned something useful!

References

Computer file. (n.d.). Retrieved February 23, 2020, from https://en.wikipedia.org/wiki/Computer_file

Directory (computing). (n.d.). Retrieved February 23, 2020, from https://en.wikipedia.org/wiki/Directory_(computing)

Path (computing). (n.d.). Retrieved December 29, 2019, from https://en.wikipedia.org/wiki/Path_(computing)

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Linux Tutorial Series

Linux Tutorial Series – 18 – Exiting a terminal session

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How do you exit a shell session in Linux? You type exit or press CTRL + D. (Shotts, 2019)⁠

mislav@mislavovo-racunalo:~$ exit

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Page 29

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Linux Tutorial Series

Linux Tutorial Series – 17 – The clear command

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If your Terminal window ever gets clogged up with old commands and old command output, type in clear to clear your Terminal window, as so:

mislav@mislavovo-racunalo:~$ clear

Keep this in mind if things get messy.

Hope you learned something useful!

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Linux Tutorial Series

Linux Tutorial Series – 16 – Command history and cursor movement

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Did you know you can use the Up/Down arrows on your keyboard to see previous commands you executed in the Linux shell? Did you know that you can use Left/Right arrows to move your cursor? (Shotts, 2019)⁠

If you did not, now you do. If you did, great for you!

Hope this helped.

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Page 27

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Linux Tutorial Series

Linux Tutorial Series – 15 – Talking about time – date and cal

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Today, let’s talk about two time-related commands in the shell. They are called date and cal. (Shotts, 2019)⁠

date gives you the current time:

mislav@mislavovo-racunalo:~$ date

Sun 22 Dec 2019 12:11:15 PM CET

cal gives you the calendar:

mislav@mislavovo-racunalo:~$ cal

December 2019

Su Mo Tu We Th Fr Sa

1 2 3 4 5 6 7

8 9 10 11 12 13 14

15 16 17 18 19 20 21

22 23 24 25 26 27 28

29 30 31

Obviously, applications of this are vast. Let’s say you freeze yourself and wake up 70 years in the future. Of course you’re not going to ask some human what year is it! That would be ludicrous! Instead, you will find the first computer with Linux and run the commands you learned from this article. I just saved your life 70 years in the future. You are welcome.

References

Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Page 28

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Linux Tutorial Series

Linux Tutorial Series – 14 – Starting a shell session

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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!

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Linux Tutorial Series

Linux Tutorial Series – 13 – What is a command?

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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

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Linux Tutorial Series

Linux Tutorial Series – 12 – What is a shell?

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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

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Linux Tutorial Series

Linux Tutorial Series – 11 – Checkpoint

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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!