Some time back, I created the Adding a Location to the Windows Path blog post to help readers make better use of some of my book examples. Adding a location to the path makes it possible for Windows to locate applications with greater ease. However, that post didn’t make it clear that a space in a path would cause problems. For example, a path such as, C:\Windows; C:\Python33 (note the space) won’t work. In order for the path to work, each individual path must be separated from the others with just a semicolon, such as C:\Windows;C:\Python33. If you’ve added a path to your Windows setup and find that Windows can’t locate the applications you want to use, please check for an unwanted space in the path.
The limitation on using spaces in a path makes sense because you also have to restrict their use at the command line. For example, typing Dir /A D (with a space between the A and the D) will produce an error. In order to obtain the correct results, you must type Dir /AD and press Enter. The reason the space causes a problem is because the command processor treats spaces as a delimiter, a separator between command elements. The space tells the command processor that one element has ended and a new one has started.
Spaces can creep into commands with relative ease. All it takes is a relatively simple tap on the spacebar at the wrong time. In addition, spaces can be hard to spot when you use certain fonts. When working in an editor to create batch files or other permanently stored command forms, always use a mono-space font, such as Courier New, to make spaces easier to spot. The point is to look for unwanted spaces when a command line feature doesn’t work properly and you know you have typed the correct command.
As a reminder from my books, the command line can also be case sensitive in some cases. Make sure you check your commands to ensure they’re formatted correctly. Let me know about your book-specific command line issue at John@JohnMuellerBooks.com.