Merge pull request #199 from LibraryCarpentry/iss99

Author: kaitlinnewson

_episodes/01-intro-shell.md

@@ -24,15 +24,14 @@ It is the definitive example of a "command line interface", where instructions a
 
 Using a shell sometimes feels more like programming than like using a mouse. Commands are terse (often only a couple of characters long), their names are frequently cryptic, and their output is lines of text rather than something visual like a graph. On the other hand, with only a few keystrokes, the shell allows you to combine existing tools into powerful pipelines and to handle large volumes of data automatically. This automation not only makes you more productive, but also improves the reproducibility of your workflows by allowing you to save and then repeat them with a few simple commands. Understanding the basics of the shell provides a useful foundation for learning to program, since some of the concepts you will learn here—such as loops, values, and variables—will translate to programming.
 
-The shell is one of the most productive programming environments ever created. Once mastered, you can use it to experiment with different commands interactively, then use what you have learned to automate your work. 
+The shell is one of the most productive programming environments ever created. Once mastered, you can use it to experiment with different commands interactively, then use what you have learned to automate your work.
 
 In this session we will introduce task automation by looking at how data can be manipulated, counted, and mined using the shell. The session will cover a small number of basic commands, which will constitute building blocks upon which more complex commands can be constructed to fit your data or project. Even if you do not do your own programming or your work currently does not involve the command line, knowing some basics about the shell can be useful.
 
 *Note to Lesson Instructor: Consider providing an example here of how you’ve used the Unix shell to solve a problem in the last week or month*
 
-
 ### Where is my shell?
 
-The shell is a program that is usually launched on your computer much in the way you would start any other program. However, there are numerous kinds of shells with different names, and they may or may not be already installed. The shell is central to Linux-based computers, and macOS machines ship with Terminal, a shell program. For Windows users, popular shells such as Cygwin or Git Bash provide a Unix-like interface, but may need to be installed separately. In Windows 10, the PowerShell natively provides that functionality.
+The shell is a program that is usually launched on your computer much in the way you would start any other program. However, there are numerous kinds of shells with different names, and they may or may not be already installed. The shell is central to Linux-based computers, and macOS machines ship with Terminal, a shell program. For Windows users, popular shells such as Cygwin or Git Bash provide a Unix-like interface, but may need to be installed separately. In Windows 10, [the Windows Subsystem for Linux](https://docs.microsoft.com/en-us/windows/wsl/install) also gives access to a Bash shell command-line tool.
 
 For this lesson, we will use Git Bash for Windows users, Terminal for macOS, and the shell for Linux users.