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

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Which keys can be used to access the command history?

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

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Which character do command line options conventionally start with?

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

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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

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

	working directory
	user name
	host name
	time and date

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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 

ExpandAnswer:

     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.

ExpandAnswer:

     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.

ExpandAnswer:

      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.

ExpandExplanation:

      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.

ExpandExplanation:

      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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