Difference between revisions of "Introduction to Linux in HPC/The Command Line"

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Introduction to Linux in HPC/The Command Line
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(Created page with "__TOC__ === Video === <!--T:5--> <youtube width="600" height="400" right>IfD9IPixgpo</youtube> [https://git-ce.rwth-aachen.de/hpc.nrw/ap2/tutorials/linux/-/blob/master/Slid...")
 
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{{Warning|mode=info|text= '''no tips in this section'''}}
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{{Warning|mode=info|text= '''Working directory in console reminds user, where they are. (page 3)'''}}
  
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{{Warning|mode=warn|text= '''no warning in this section'''}}
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{{Warning|mode=warn|text= '''
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    In command line user may forget where they are. (page 2)</br>
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    Child processes may stop, if parent shell exits. (page 2)
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'''}}
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=== Exercises in Terminal === <!--T:5-->
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1. What's your username on a Linux computer?
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  There are two ways to find your username on a Linux computer
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  {| role="presentation" class="wikitable mw-collapsible mw-collapsed"
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    | <strong>Answer:</strong>
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    |-
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    |
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      1. In the command line prompt, e.g. [username@hostname ~]$ , you can find your username as username directly.
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      2. The Linux command whoami can also show your username.
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    |}
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2. What's the hostname of a Linux computer?
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  There are two ways to find the hostname on a Linux computer.
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  {| role="presentation" class="wikitable mw-collapsible mw-collapsed"
 +
    | <strong>Answer:</strong>
 +
    |-
 +
    |
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      1. In the command line prompt, e.g. [username@hostname ~]$ , you can find the hostname as hostname directly.
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      2. The Linux command hostname can also give you the hostname.
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    |}
 +
           
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3. What's your current working directory on a Linux computer?
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    There are two ways to find your current working directory on a Linux computer.
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    {| role="presentation" class="wikitable mw-collapsible mw-collapsed"
 +
    | <strong>Answer:</strong>
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    |-
 +
    |
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      1. In the command line prompt, e.g. [username@hostname ~]$ , you can find your current working directory is ~, which means your $HOME directory.
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      2. The Linux command pwd can also show your current working directory.
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    |}
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4.  Use up- and down-arrow keys to see the command history.
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    {| role="presentation" class="wikitable mw-collapsible mw-collapsed"
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    | <strong>Explanation:</strong>
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    |-
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    |
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      The up- and down- arrow keys can be used to navigate command history.
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    |}
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5.  Run sleep 1h command and wait, then use Ctrl-C to kill it.
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    {| role="presentation" class="wikitable mw-collapsible mw-collapsed"
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    | <strong>Explanation:</strong>
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    |-
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    |
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      sleep 1h puts the terminal into idle, e.g. terminal is doing nothing, for 1 hour.
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      Ctrl-C kills the current command. In this exercise it's sleep 1h.
 +
    |}

Revision as of 17:01, 1 October 2020

Video

Linux Introduction Slides 25 - 31 (7 pages)

Slide Layout

   page 1: 
       You type commands in command line to use Linux
       Similar things: console, terminal, CLI and shell (interchangeable in this course)
       command line: advantages (fast) vs. disadvantages (hard to master)
   page 2: 
       Shell in Linux is widely used.
       Warnings:
           User may forget where they are.
           Child processes may stop, if parent shell exits.
   page 3: 
       Elements in console:
           User name
           Host name
           Working directory: reminder for user (where they are)
           Command prompt
   page 4: 
       Elements in console (cont.):
           Command and its options
           Output
           Current command running or new command prompt
   page 5: 
       Demo 1: (slide 15 sec + terminal 45 sec)
           run command
           arrow keys for history
           tab key for auto-completion
           Ctrl-C to abort
   page 6: 
       Warning: command is always case-sensitive
       command line options: minus sign: double minus vs. single minus
   page 7: 
       Demo 2: (slide 15 sec + terminal 30 sec)
       use internet for help
       man page
       built-in help


Quiz

Which keys can be used for command history?

A. up- and down-arrow keys
B. Page-up and Page-down keys


Info:  Working directory in console reminds user, where they are. (page 3)


Warning:  
   In command line user may forget where they are. (page 2)

   Child processes may stop, if parent shell exits. (page 2)


Exercises in Terminal

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

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

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.

4.  Use up- and down-arrow keys to see the command history.

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