Master the command line: Navigating files and folders

If you’ve been using a Mac for any length of time, you know that it’s more than just a pretty point-and-click, window-and-icon interface. Beneath the surface of the operating system is an entire world that you can access only from the command line. Terminal (in your /Applications/Utilities folder) is the default gateway to that command line on a Mac. With it, instead of pointing and clicking, you type your commands and your Mac does your bidding.

Why would you want to do that? For almost all of your computing needs, the regular graphical user interface is enough. But the command line can be handy when it comes to troubleshooting your Mac, to turn on “hidden” settings, and other advanced chores. It’s a good idea for anyone who isn’t an utter beginner to be familiar with it.

If you aren’t already familiar with your Mac’s command-line interface. First up: How to navigate the file system from the command-line prompt.

The prompt

By default, when you open Terminal, the first thing you’ll see is something like this:

Last login: Tue Apr 23 13:40:35 on ttys000
walden:~ kirk$ 

The first line shows the last time you logged into your Mac via the command line; that’s the current time, when you’re using Terminal. The second line is the prompt, and while it can change from system to system depending on configuration, by default it contains several bits of information.

In my prompt, walden is the name of my Mac (same as the name in the Sharing pane of System Preferences), and kirk is my user name. The ~ shows where I am in the file system of my Mac; ~ is a shortcut that means the current user’s home folder. (In the Finder, that’s the folder with your user name and the house icon.) Finally, the $ is a character that the bash shell (the default interface that Terminal uses) displays to indicate that it’s ready to accept a command.

What’s in a folder

When you first get to the command line, you’re in your home folder. While you’re there—or when you’re in any folder (directory in Unix-speak)—you might want to know what’s in it. To do that you use the ls (or list) command. Type ls and press the Return key, and you’ll see the folders (and/or files) in the current directory.

The output of the plain ls command is pretty sparse; it shows you the names of files and folders contained in the current directory (including some familiar ones such as Movies, Music, Pictures, and so on). Fortunately, you can add a number of optional switches to the ls command that allow you to see more information. So, for example, try typing ls -l (that’s a lower-case L), then pressing Return. You’ll see something like this: