The Very Basics

Welcome to Comfort on the Command Line.

I’ll be writing a series of posts to help you gain comfort with the UNIX command line interface (cli). If you’re already a cli wizard, then this may not be the guide for you.

What is the command line interface (cli)?

There are different ways to interact with a computer. The most common is the graphical user interface (gui) which you probably use every time you use a computer. Graphical user interfaces usually have things like windows, icons and menus. The main way to interact with a graphical user interface is with the mouse, though keyboard shortcuts are also supported.

Another way to interact (interface) with a computer is by typing a command on one line, pressing enter, waiting for the computer to run that command, and seeing the output of that command on the next line. This is how a command line interface works. You type a command, hit return, wait for the computer to execute that command, and then see the computer’s response. If you remember DOS, then you know what a command line interface (cli) looks like.

When you first enter the command line interface, you will see something that looks a bit like this:


We call this $> thing the prompt, as in - the computer is prompting you to do something… anything. Not that. Not that either, no no - don’t you know what I need? Oh right, you don’t, how could you I’m just a prompt.

Where was I? Oh right, the prompt. Where can I find this prompt? You should have a terminal program somewhere on your system. On a Mac it is actually called Terminal, and it’s in the Utilities folder inside your Applications folder (notice the icon even has a prompt!). On Linux systems, there are several terminal programs available and due to the vastness of the Linux ecosystem, you should probably type this into your favourite search engine right now:

“xxx Linux how to get to the terminal”

Where xxx is your particular Linux distribution (Ubuntu, RedHat, CentOS, Gentoo, etc).

If you are running a BSD (I’m impressed and think you are cool - I also run a BSD) then there will also be various possible ways to get to a terminal program and you should do the same search I recommend for the Linux people, except replace “Linux” with “BSD” and xxx with your particular flavor of BSD (Open, Free, Net, Dragonfly).

Even Windows has a command line interface, and you can run it by typing cmd in the “run program” dialog from the start menu (assuming Windows still has a start menu). This is the last mention we will make of Windows since this guide is about the UNIX cli and Windows doesn’t have one of those.

Ok, first homework assignment. Go find your terminal program. Figure out how to open it, close it, resize it, etc.

That’s enough for today, stay tuned, in our next episode I’ll actually show you some things you can do with your new found terminal program. In the mean time – feel free to just keep the window open somewhere on your system, this will impress people.

p.s. At the end of these posts I’ll recap new terms

New Terms

  • cli - command line interface

  • gui - graphical user interface

  • terminal - a program that allows you to interact with the computer via the command line interface

  • prompt - the weird $> looking thing that means the computer is waiting for you to type something.

p.p.s. There’s another program involved as well, it’s called the shell, but I’m just going to ignore that for now.