SocSci Computing Services Help Pages

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====== How do I use a Linux Command-line Interface? ======

This page is for you if you are getting access to a Linux server and you need to learn how to use the command-line interface to use the server.



===== 1. Obtaining software =====
Step one is to obtain some terminal software. If you are on a Linux or a Mac computer, you already have this! Look for your Terminal application. If you are on a Windows PC, you might need to install either an SSH client, or a terminal emulator. You have a couple options:

  - Try opening the Windows Terminal and see if you can use the ''ssh'' command (it might be installed already)
  - [[https://www.chiark.greenend.org.uk/~sgtatham/putty/download.html|Download PuTTY.exe on this website]]
  - [[https://cygwin.com/install.html|Install Cygwin]] - this is a much more advanced option, not recommended for the faint of heart as it installs a linux emulation layer on top of Windows and requires selection of desired packages to be installed.
  - [[https://docs.microsoft.com/en-us/windows/wsl/install-win10|Install the Microsoft "Bash on Windows" subsystem for linux]] - this might be appropriate if you want a more officially supported linux emulation layer on top of Windows. If you are curious, this installs a debian-like linux distro, complete with "apt" to install desired packages.



===== 2. Open the terminal or connect to the remote Linux server =====

If you installed either options 3. Cygwin or 4. Bash on Windows above, then you can practice the commands and tutorials listed below on your local computer. If you are on a Linux or Mac computer, you can also practice on your local computer.

If your Windows Terminal application comes with the ssh command, you can run the command below to connect to a remote Linux server.

  * Open the terminal application, then run this command to connect to a remote linux system using SSH:<code>
ssh <username>@<servername>
#for example: ssh jnilsson@nexus.socsci.uci.edu
</code>

Or, if you installed PuTTY.exe or another SSH client program, you will need to connect to the remote linux server.

  * PuTTY and enter the hostname of the server, optionally set any connection options you need, then click on Open. It will prompt you for your username and password, but when you type the password, it will not print anything to the screen. This is normal.

===== 3. Run through a tutorial =====

There is a great resource available online. Please keep your terminal open side by side with a browser window and run through the tutorial here:

  * [[http://swcarpentry.github.io/shell-novice/]]








===== 4. Important commands to know =====

Here are the most important commands to make sure you are familiar with:

  * ''passwd'' (use this to change your password. If you have not done this yet, do it now!)
  * ''pwd''
  * ''ls''
  * ''cd''
  * ''mkdir''
  * ''rmdir''
  * ''cp''
  * ''mv''
  * ''rm'' (be very careful with this! It might not ask you to confirm before deleting)
  * ''vim'', ''emacs'', or ''nano'' (text editor of your choice)
  * ''cat''
  * ''less'' or ''more''
  * ''grep''
  * ''sort''
  * ''tail''
  * ''head''


===== 5. Important shell concepts =====

  * Output redirection: ''>'' or ''%%>>%%''
  * Input redirection: ''<''
  * Piping commands together: ''|''
  * Shell globs and character pattern matching: ''[A-Za-z0-9]'', ''*'', ''?''
  * Regular expressions to use with ''grep'' - [[https://regexone.com/|see this tutorial]]