Command line 1 (Windows)

• The three Command Line lessons are based on the wonderful Software Carpentry’s materials.
• Windows users will work through a special breakout session for Command Line 1 only. We will cover:
  • Setup
  • 1. Introducing the Shell
  • 2. Navigating Files and Directories
  • 3. Working with Files and Directories

What is the shell? Why and how do we use it?

• The shell is a program that runs other programs, typically in a Unix environment.
• We use the shell to interact with the computer on the command line (CLI ~ GUI).
• The command-line-based window that runs a shell is called a console or a terminal.
• The Unix philosophy is that you can pipe (chain) together small commands, each of which does one thing well, to do something complex. You can’t do this in a GUI.
• bash = ‘Bourne again shell’ (the original Bourne shell is sh; others include csh, ksh, tcsh, zsh).
• Learn the shell on a need-to-know basis.

Our choice of shell: git bash

• We will be learning the bash shell.
• When you downloaded Git, you also downloaded Git bash <screenshot>, the command line interface.
• You may have been using cmd.exe <screenshot> or Windows Powershell <screenshot>, both native to Windows. Though each has its own benefits and drawbacks, for the purposes of this institute we will have all Windows users learn and use Git bash.
  • You might have heard of “Ubuntu Bash on Windows 10”. We do not recommend it—ask us why later!
• Why is learning bash a good idea?

Git bash vs. Windows command lines vs. regular bash

• The Git bash filesystem adopts a Unix-like convention: it uses / as the path separator, and absolute paths start with /c/, /d/, etc. (So, /c/Users/narae instead of C:\Users\narae in cmd.)
• Git bash is missing some commands that are included in regular bash, e.g., nano, sudo, and man.
  • nano is a text editor. You can substitute Notepad, which you can run using notepad myfile.txt.
  • sudo allows you to change features that require elevated administrative permissions. (If you ever get to try it, use it with caution.)
  • man displays a command manual, and there is no equivalent in Git bash. You can look up commands on line at https://ss64.com/bash/.
• Git bash requires the use of winpty when running certain Windows applications that are meant to run within cmd. For example, to run an interactive python session, you should execute winpty python.

Getting oriented

• If you type a command and find yourself on a blank line with nothing happening: you typed an incomplete command, and should abort it with Ctrl+c.
• When you see $ (shell prompt): the shell is waiting for you to provide input.
• When you type $: you’re beginning to type a variable name.
• When you see > (shell continuation prompt): you’ve started entering multiple-line input, and the shell is waiting for the next line. Abort if this not what you meant to do.
• When you type >: you’re writing output into a file, instead of displaying it on the screen. More on this in Command Line 2.

Files and directories

• We will work from the Software Carpentry lessons:
  • 2. Navigating Files and Directories
  • 3. Working with Files and Directories