Shell - Revision history

Jan-steiner-ac29@uni-siegen.de: Removed broken link.

2020-05-15T09:28:01Z

Removed broken link.

Daniel-schurhoff-de23@rwth-aachen.de at 13:06, 3 September 2019

2019-09-03T13:06:40Z

Daniel-schurhoff-de23@rwth-aachen.de at 13:05, 3 September 2019

2019-09-03T13:05:58Z

Ds019135 at 06:50, 20 June 2018

2018-06-20T06:50:40Z

Nina-loseke-fd7a@rwth-aachen.de at 13:30, 20 April 2018

2018-04-20T13:30:02Z

Christian-wassermann-e30b@rwth-aachen.de at 10:51, 16 April 2018

2018-04-16T10:51:55Z

Christian-wassermann-e30b@rwth-aachen.de: /* Utilities */

2018-04-09T15:12:00Z

Utilities

Christian-wassermann-e30b@rwth-aachen.de: /* Getting System Info */

2018-04-09T15:05:22Z

Getting System Info

Christian-wassermann-e30b@rwth-aachen.de: /* Doing Stuff with Files and Directories */

2018-04-09T15:02:54Z

Doing Stuff with Files and Directories

Christian-wassermann-e30b@rwth-aachen.de: /* Navigating the Unix File System */

2018-04-09T15:00:32Z

Navigating the Unix File System

← Older revision		Revision as of 09:28, 15 May 2020
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	== References ==		== References ==
	[http://www.karlin.mff.cuni.cz/~hron/NMNV532/ShellIntro.pdf A short info with a good basic command reference]		[http://www.karlin.mff.cuni.cz/~hron/NMNV532/ShellIntro.pdf A short info with a good basic command reference]
−
−	~~[http://linux.org.mt/article/terminal/ A longer linux-shell tutorial]~~

@@ Line 1: / Line 1: @@
 [[Category:Basics]]
 == General ==
 The Shell or commandline is a program to interact with a given computer (or supercomputer). Contrary to a graphical user interface (e.g. Windows or Mac Desktop) which most desktop machines offer today, the shell seems simplistic, although daunting at the same time, because it requires the user to have a certain knowledge of the available commands and their uses. However, even with a few basic commands, the shell can be used productively and become a powerful tool in your toolbox. This power combined with the fact that the shell itself uses almost no resources is the reason, why it is still widely used on nearly every supercomputer.

← Older revision		Revision as of 13:05, 3 September 2019
Line 1:		Line 1:
		+	[[Category:Basics]]
		+
	== General ==		== General ==
	The Shell or commandline is a program to interact with a given computer (or supercomputer). Contrary to a graphical user interface (e.g. Windows or Mac Desktop) which most desktop machines offer today, the shell seems simplistic, although daunting at the same time, because it requires the user to have a certain knowledge of the available commands and their uses. However, even with a few basic commands, the shell can be used productively and become a powerful tool in your toolbox. This power combined with the fact that the shell itself uses almost no resources is the reason, why it is still widely used on nearly every supercomputer.		The Shell or commandline is a program to interact with a given computer (or supercomputer). Contrary to a graphical user interface (e.g. Windows or Mac Desktop) which most desktop machines offer today, the shell seems simplistic, although daunting at the same time, because it requires the user to have a certain knowledge of the available commands and their uses. However, even with a few basic commands, the shell can be used productively and become a powerful tool in your toolbox. This power combined with the fact that the shell itself uses almost no resources is the reason, why it is still widely used on nearly every supercomputer.

@@ Line 19: / Line 19: @@
 Furthermore you can get help for most commands by appending <code>-h</code> or <code>--help</code> to show the corresponding help message of the executed command. Additionally the so-called manual pages (or short: man pages) provide you with a detailed description for the specified command. Type <code>man ls</code> to look at the man page for the <code>ls</code> command, scroll with your arrow keys and press <code>q</code> to exit.
-== Navigating the Unix File System ==
+== Navigating the File System ==
 The following commands tell you, where you are, take you somewhere else and show you what is there:
 {| class="wikitable" style="width: 45%;"

← Older revision		Revision as of 13:30, 20 April 2018
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	Windows has the DOS commands (available with cmd) or the PowerShell (ps), which is different syntax-wise and will not be covered in too much detail, since most supercomputers run Unix systems.		Windows has the DOS commands (available with cmd) or the PowerShell (ps), which is different syntax-wise and will not be covered in too much detail, since most supercomputers run Unix systems.
		+
		+
		+	__TOC__
		+

	== Usage ==		== Usage ==

@@ Line 46: / Line 46: @@
 | vim || || Opens the [[vim]] text editor to modify files.
 |-
-| cat || type || Display the contents of a text file on the screen. For example: cat mp3files.txt would display the file we created in the previous section.
+| cat || type || Display the contents of a text file on the screen. For example: cat MyFile.txt would display the contents of the file.
 |-
 | head || || Display the first few lines of a text file. Example: head /etc/services
@@ Line 54: / Line 54: @@
 | tail -f || || Display the last few lines of a text file, and then output appended data as the file grows (very useful for following log files!). Example: tail -f /var/log/messages
 |-
-| cp || copy || Copies a file from one location to another. Example: cp mp3files.txt /tmp (copies the mp3files.txt file to the /tmp directory)
+| cp || copy || Copies a file from one location to another. Example: cp MyFile.txt /tmp (copies the MyFile.txt file to the /tmp directory)
 |-
-| mv || rename, ren, move || Moves a file to a new location, or renames it. For example: mv mp3files.txt /tmp (copy the file to /tmp, and delete it from the original location)
+| mv || rename, ren, move || Moves a file to a new location, or renames it. For example: mv MyFile.txt /tmp (copy the file to /tmp, and delete it from the original location)
 |-
-| rm || del || Delete a file. Example: rm /tmp/mp3files.txt
+| rm || del || Delete a file. Example: rm /tmp/MyFile.txt
 |-
 | mkdir || md || Create an empty directory. Example: mkdir /tmp/myfiles/
@@ Line 102: / Line 102: @@
 | grep || Search for a pattern in a file or program output and only print matching lines. For example, to find out which TCP network port is used by the “nfs” service, you can do this: <code>grep "nfs" /etc/services</code>
 |-
-| sort || Sort a file or program output. Example: sort mp3files.txt
+| sort || Sort a file or program output. Example: sort MyFile.txt
 |-
 | su || “Switch User”. Allows you to switch to another user's account temporarily.

@@ Line 94: / Line 94: @@
 | '''Linux Command''' || '''Description'''
 |-
-| clear || Clear the screen
+| clear || Removes the scrollback history from your shell and moves the current prompt to the top of the screen.
 |-
-| echo || Display text on the screen. Mostly useful when writing shell scripts. For example: echo “Hello World”
+| echo || Print text to the screen. Most useful when writing shell scripts, e.g. for logging progress or printing results. For example: <code>echo “Hello World”</code>
 |-
 | less || An improved replacement for the “more” command. Allows you to scroll backwards as well as forwards.
 |-
-| grep || Search for a pattern in a file or program output. For example, to find out which TCP network port is used by the “nfs” service, you can do this: grep "nfs" /etc/services This looks for any line that contains the string “nfs” in the file “/etc/services” and displays only those lines.
+| grep || Search for a pattern in a file or program output and only print matching lines. For example, to find out which TCP network port is used by the “nfs” service, you can do this: <code>grep "nfs" /etc/services</code>
 |-
 | sort || Sort a file or program output. Example: sort mp3files.txt

@@ Line 76: / Line 76: @@
 | id || Print your user-id and group id's
 |-
-| du || Disk Usage in a particular directory. “du -s” provides a summary for the current directory.
+| du || Disk Usage in a particular directory. <code>du -s</code> provides a summary for the current directory.
 |-
-| top || Displays CPU processes in a full-screen GUI. A great way to see the activity on your computer in real-time. Type “Q” to quit.
+| top || Displays all currently running processes on your system in full-screen. A great way to see the activity on your computer in real-time. Type <code>q</code> to quit.
 |-
 | free || Displays amount of free and used memory in the system.

@@ Line 60: / Line 60: @@
 | rm || del || Delete a file. Example: rm /tmp/mp3files.txt
 |-
-| mkdir || md || Make Directory. Example: mkdir /tmp/myfiles/
+| mkdir || md || Create an empty directory. Example: mkdir /tmp/myfiles/
 |-
-| rmdir || rd, rmdir || Remove Directory. Example: rmdir /tmp/myfiles/
+| rmdir || rd, rmdir || Delete an empty directory. Example: rmdir /tmp/myfiles/
 |}

@@ Line 32: / Line 32: @@
 | ls -l || dir || List files in “long” format, one file per line. This also shows you additional info about the file, such as ownership, permissions, date, and size.
 |-
-| ls -a || dir /a || List all files, including “hidden” files. Hidden files are those files that begin with a “.”, e.g. The .bash_history file in your home directory.
+| ls -a || dir /a || List all files, including “hidden” files. On Unix systems hidden files are those beginning with a “.”, e.g. The .bash_history file in your home directory.
 |}