Introduction to Linux in HPC/The Command Line

This part of the tutorial introduces one of the most important tools in Linux-based systems: the command line. The command line is basically a text interface for your computer and it can be pretty daunting at first if you are used to a graphical user interface (GUI). This short tutorial explains the basics enabling you to get started straight away!

Video

( Slides as pdf)

Quiz

Which keys can be used to access the command history?

	up- and down-arrow keys
	page-up and page-down keys

Which character do command line options conventionally start with?

	the dollar sign
	the dash sign (hyphen)
	the greater-than sign

What happens if the control and c keys (Ctrl+C) are pressed simultaneously on the command line?

	the current command is aborted
	a script starts running in the shell
	highlighted text is copied to the clipboard

Which one of these is not (normally) an element of the console prompt statement?

	working directory
	user name
	host name
	time and date

How can I list all available commands if I don’t know the exact name of the command, for example?

	press the enter key
	read the man pages
	press the tab key
	use the --help option

Info:

Working directory in console reminds user, where they are. (page 27)

Warning:

In command line user may forget where they are. (page 26) Child processes may stop, if parent shell exits. (page 26)

Exercises in Terminal

1. What's your username on a Linux computer?
  There are two ways to find your username on a Linux computer 

Answer:

     1. In the command line prompt, e.g.[username@hostname ~]$ , you can find your username as username directly.
     2. The Linux command whoami can also show your username.

2. What's the hostname of a Linux computer?
  There are two ways to find the hostname on a Linux computer.

Answer:

     1. In the command line prompt, e.g. [username@hostname ~]$ , you can find the hostname as hostname directly.
     2. The Linux command hostname can also give you the hostname.

3. What's your current working directory on a Linux computer?
   There are two ways to find your current working directory on a Linux computer.

Answer:

      1. In the command line prompt, e.g. [username@hostname ~]$ , you can find your current working directory is ~, which means your $HOME directory.
      2. The Linux command pwd can also show your current working directory.

4.  Use up- and down- (↑ and ↓) arrow keys to see the command history.

Explanation:

      The up- and down- (↑ and ↓) arrow keys can be used to navigate command history.

5.  Run sleep 1h command and wait, then use Ctrl-C to kill it.

Explanation:

      sleep 1h puts the terminal into idle, e.g. terminal is doing nothing, for 1 hour.
      Ctrl-C kills the current command. In this exercise it's sleep 1h.

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