76 lines
3.2 KiB
ReStructuredText
76 lines
3.2 KiB
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Appendix C Command line
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The command line or CLI is text interface to your computer and an alternative to graphical user interfaces like windows. It typically involves typing text commands into a terminal to perform some operation. Although not necessary to learn, it can be helpful. The terminal which can be launched from :kbd:`Control + Alt + T` is a command line running in a window.
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An exhaustive tutorial on the command line is a bit beyond the scope of the manual. The man command brings up the user manual and can be used to learn more about a commands use, its options, and inputs. If you wanted to learn more about the df (disk free) command, enter the following into a command line and press :kbd:`enter` :
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man df
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This will show you the user manual for the df command containing and explanation of the command and other useful information. For example is the -h option gives a human readable output. If the manual is way too long you can press the :kbd:`/` key and type in what you want to search for. To scroll up and down in a manual page press :kbd:`Up arrow` or :kbd:`Down arrow`. To quit a man page press :kbd:`q`.
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df -h
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will make a much nicer output than
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.. code::
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df
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To list files on the current file system one of the most important commands to know is ls.
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ls
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will show the files in your current directory and the man page lists more options such as viewing all files or long listing.
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To change to another directory an important command is
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cd [dir]
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where [dir] is the directory you want to switch to. Another thing that is useful is you can append .. after cd to make it go up one level.
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Many command line commands have what are called options that use one or sometimes two :kbd:`-` to type before options that allow you to do different options on different commands which checking the man page to see what options for each command.
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There is also the command line for managing and installing packages which is beyond the scope of this appendix but please see `apt package management https://ubuntu.com/server/docs/package-management>`_ for how to insert and remove packages from the command line.
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If you need to edit a text file from the command line the easiest editor included is nano so to edit a file from the command line if you broke something run
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nano [file]
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where you replace [file] with the file you want to edit.
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If you want to stop something running in the terminal press :kbd:`Control +C`.
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If you want just to see the contents of a file on standard output run
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cat [filename]
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If you have a command and you don't want to type the whole thing out you can press the :kbd:`tab` key. If this does not work press :kbd:`tab` again and see the list of available commands to run. This process is called tab completion.
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If you want a command to run if the first completes run
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command 1 && command 2
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One of the most powerful uses of the command line is called a pipe which allows you to take the output of one command and pipe it to a second to this for example
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.. code::
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lspci |less
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. Also | is called the pipe character.
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