Introduction to Linux

Introduction

Try It

  • To get the most out of Linux, you'll want to learn to use the command line to get things done. Linux is based around an operating system called UNIX that was first devised and written in 1969. Computers weren't really used with mice, touch screens or graphics back then. Many used line printers to produce their output rather than a monitor; thankfully, things have moved on.
  • Many of the commands you'll learn are unchanged since the original UNIX release. Depite these commands possibly being older than your parents, they are used daily on the vast majority of the World's most powerful computers.
  • In this lesson, we'll learn to navigate around your files and look at what's in them.
  • We'll use this superb emulator by Fabrice Bellard
  • Or…
Click here for pop-up window version
  • Once the session has booted up, type:
cd /home
cp -R * /tmp/
cd /tmp/treasure_hunt

Try It

  • We're going on a treasure hunt.
  • In the treasure directory that you're currently in, there are more directories and some files within them.
  • Many of these files contain jokes. One of them contains a secret code that you can use to collect your silver badge for this lesson.
  • You'll need to learn to use three commands to complete this exercise.

Present Working Directory

  • You'll need to know where you are in your filesystem.
pwd
  • Present Working Directory. Outputs the current directory you're in.
  • If you've followed the above instructions and try this, you should see that you're currently working in…
    • /tmp/treasure_hunt

Listing directory contents

  • Just like when you use 'My Computer' in Windows to browse your documents and files, it's useful to see what files you have in different directories.
ls
  • LiSt. Shows a list of the files and directories in the current directory.
  • Pro tip: You can get a more detailed list if you use ls -l instead.

ls-l.png

  • In the shot above, you can see the time and date when each file was last modified to the left of each file name.
  • Entries which are directories (like pages and source in my example) have the letter 'd' on the far left-hand side of the column. Some Linux systems will also change the colour of the directory names for you, like in the image above.
  • The size of the file in bytes is shown to the left of the month the file was last modified.
  • The username and group of the person who created the file is shown here too.
  • Pro tip: Tap the up and down arrows on the keyboard to browse your previous commands.

Change Directory

  • Sometimes, we'll want to work in a different directory (or folder, as you'd say in Windows)
cd NAME_OF_DIRECTORY
  • Change Directory to somewhere else. You could type cd a for instance to move into directory a.
  • At the moment, you should be able to see four directories, imaginatively called a, b, c and d. Let's Change Directory into a…
  • Type: cd a
  • Now let's LiSt the files in this directory. Type: ls
  • There are three text files in here. We'll have a look inside them in a moment.
  • For now though, we'll need to get back to the previous directory. This is done as follows:
  • cd ..
  • In Linux type Operating Systems, .. means 'back one level'. You can use a few of them at a time to navigate around more quickly. E.g. cd ../.. to drop back two directory levels, or cd ../b to drop back a level, then change into the b directory if you were already working inside a.
  • Task: Use pwd to get your bearings, then navigate into the a directory once more.

Concatenate

  • This command is actually short for conCATenate, which means to add one thing to the end of another. While it can do this, its more commonly used by Linux users to quickly see the contents of files.
cat FILENAME
  • Assuming you're in the a directory, type ls to see whats in there.

cat.png

  • Let's see what's inside the otherfile.txt document. Type cat ot like in the screenshot above.
  • Linux users don't like to type too much - as there are no other files in here that start with ot, you can hit the tab key to auto-complete (you'll want to do this a lot once you get used to it), then hit enter to run the command.
  • The contents of the file will now be displayed.

Badge It

  • Attempt the badge tasks below. If you're not sure how to navigate the filesystem, the video tutorial below goes over it again, with examples, to help you achieve the badge.
  • Silver: Explore the treasure_hunt directory and its sub-directories, and cat the different files until you find the secret password. Screenshot the file content with the password and upload
  • Gold: In the file you created for the silver badge, add a short explanation of what ls, cd, cat and pwd do in a Linux terminal.
  • Platinum: Make a new directory called LinuxChamp inside the /tmp/ directory, and move one of the joke files from the earlier directory into it. Screenshot the results of the pwd and ls command from the terminal as evidence you've completed the task.
  • BONUS TASK: If you've completed the tasks, why not try playing a game of Terminus? It's a great way to practice your commands. The only thing to note is that they prefer you to use less instead of cat to open the files you encounter on your journey…