Linux Terminal

In this document, we will be learning the basics of the Linux Terminal. We will go through all the basic commands with examples for each.

What is a terminal?

It's a part of every system (irrespective of Operating System) that helps you control the system from a very stripped down level (without a Graphical User Interface). Programs or Commands can be run from here to perform some task on the system.

It is a very powerful tool and most of the time, GUI applications have these commands running in the back when you click buttons to perform actions.

You can open up a terminal on Fedora by hitting the keybind Ctrl+Shift+T.

Directories

A directory is like a folder on your computer under which files or other folders can exist.

In Linux, everything on your system, including the hardware devices that you have connected to your computer will be available for use as a file. It's a UNIX system convention.

The / directory in your system is the root of your file system. It has everything that is on your storage that is mounted.

Here are some of the directories in / and description of what they hold.

In the terminal type in this command

cd Desktop

The cd command is used to change your current working directory (the current folder that you have open) to the directory that you specify. Desktop in this case.

There are some shortcut characters that you can use to make your life easier while working with directories.

The symbol ~ is used to refer to the user's home folder (/home/<user_name>).

cd

Now type

ls

The ls command is used to list out the contents of your current directory. You can use some flags to tell the command what to output.

ls -l

The -l flag can be used to long list (or vertical list) out the contents along with the permissions on each file/folder.

ls -a

The -a flag can used to show all files and folders in the current directory along with the hidden files. You can use both of the above commands in unison like this

ls -la

You can make directories inside your current directory using the mkdir command.

mkdir test

If you want to create multiple directories inside of each other, then we use the -p flag.

mkdir -p test1/test11
  • This would create a test1 directory in your current directory and create a test11 directory inside of test1.
  • If you want to remove all these directories that you created just now, you can use either rmdir or rm.
  • rmdir is used to delete directories that are empty.
rmdir test
  • This would work because test is empty. But the same thing wouldn't work with test1 as it has a test11 directory inside it.
  • So we use the rm command with the -r flag to remove it.
rm -r test1
  • The -r flag represents recursive removal. You can also use the -f flag to force remove the directories.
  • Remember, -f would remove everything even if it is read-only.
  • You can create a new file using the touch command.
touch text.txt
  • You can view the contents of this file by using the cat command.
cat text.txt
  • This wouldn't output anything as the file is empty. You can open this file right in the terminal by using nano which is a terminal based editor.
nano text.txt
  • Once you are done editing the contents you can hit Ctrl+S and Ctrl+X to save and quit.
  • You can remove this file now with rm.
rm text.txt

Super User Privileges

  • Super user privileges are admin privileges or elevated privileges given to a user in any UNIX system.
  • To execute commands as a super user, we use the su command. su stands for switch user.
  • Try executing
su -
  • Now a terminal would open with a different color to denote that you have super user privileges. In this terminal, you literally can nuke your whole system. So be careful about what you do in here.
  • To get back to your normal user terminal, type
exit
  • If you want to execute only some commands with super user privileges, you can use the wrapper command sudo.
  • This is safer as you can be sure to execute each command with the right permissions.
  • Try out this command
sudo dnf update
  • Super user privileges are required for package manager commands on any Linux system.
  • So to install packages you will be prompted to give your password.

Pipe

  • The Pipe symbol (|) is used to chain the outputs of certain commands into other commands.
  • There are several uses to this symbol, but the most common usage is to use it alongside the grep command.
  • Try this command
touch text.txt
ls | grep text.txt
  • grep is used to print out all the lines within an output or a file with text.txt in it.
  • You can pipe the output of any command into grep and get the matching lines based on your search term.