Why use the command line?

Graphical user interfaces (GUIs) exist because they make interacting with the computer (and specifically the operating system) simple. It’s easier to click and double-click on icons or pick things from menus!

But that convenience also blunts its power. When you study Computer Science, using the command line is a crucial skill… because (once you know how to use it) it’s much more powerful.

• Using the command line can be faster, especially for complex operations.

• You are being very explicit when you use it, so you need to know what you’re doing… and if you don’t (yet) it’s an explicit way to learn.

• Commands themselves are scriptable (you can put them in a file and replay them), so are ideal for automation.

• Similarly, you can issue commands from within other programs you write (for example, in Python you can use the os.system() function).

• Commands can be chained together so output from one can be “piped” to the next.

• You can control (redirect) the inputs and outputs, which is very handy for capturing output into files, which you can then use as input to other commands.

• Some commands give you a lot of power to control options, which can quickly get fiddly with GUIs.

• Most GUIs don’t make your history available; the command line has good previous command recall.

• Sometimes you don’t have access to a GUI on a remote server, so you only have the command line available.

If you’re studying Computer Science you must understand how the command line works: it’s possibly the primary way you communicate with the computer. The GUI is a layer on top of that (of course you will be familiar with that too).

You can drive most computers from the command line. We tend to focus on the Unix-like systems (that includes the Mac’s command line, and the Windows Subsystem for Linux) because they have a long history of utility, predating GUIs entirely. Window’s own command line is a little bit different, but the underlying ideas are similar.