Setting the Mac OS PATH

What is path?

PATH is a system-level vari­able that holds a list of direc­to­ries. When you enter a command in the terminal, it’s short­hand for a program with the same name. The system looks in each of the PATH direc­to­ries for the program corre­sponding to the command. When it finds a matching program, it runs it. If it doesn’t find a match, it raises an error.

To see the PATH on your system, open the terminal window and enter this command (where zsh$ repre­sents the terminal prompt, which will be different on your system):

Type return to complete the command. The result will be a list of direc­to­ries sepa­rated by : that looks like this:

The exact list may be different on your system. Now try the which command, which shows us the full path corre­sponding to a another command:

This tells us that the whoami command (which prints your user­name to the terminal) actu­ally invokes the program located at /usr/bin/whoami. The terminal finds this program by looking for whoami in each of the PATH direc­to­ries, one of which is /usr/bin.

We can always invoke a command by using its full path rather than the short­hand:

In this case, the terminal doesn’t look in the PATH direc­to­ries for whoami, because we’ve already provided a full path to whoami.

If we enter a command name that doesn’t exist in any PATH direc­tory, we get an error:

Our goal is to add the direc­tory containing racket to our PATH. Then the terminal will be able to find it.

Updating path

First, check that your Racket instal­la­tion works by going into your new Racket direc­tory and launching DrRacket. If DrRacket works, then your Racket instal­la­tion is sound.

Next, check that you know the full path to the bin subdi­rec­tory of your new Racket direc­tory. If you put this direc­tory in Applications as recom­mended, the path will be:

If you installed or moved it else­where, the path will be different. For instance, it can be conve­nient to remove the version number from the name of Racket’s instal­la­tion direc­tory, like so:

This way, you can update Racket in the future without changing the rest of the config­u­ra­tion below.

Either way, we’ll refer to this Racket path as /YOUR/PATH/TO/bin. So when you see /YOUR/PATH/TO/bin in commands below, substi­tute your actual path to the Racket bin subdi­rec­tory.

You can test this path from the terminal: append /racket to the path and enter it as a command. This should start Racket (include the surrounding double quotes around the whole thing):

If this doesn’t work, either the path to Racket is mistyped, or there’s an error in your Racket instal­la­tion.

If it does work, type ctrl+D or (exit) to quit Racket. Next, you need to add this path to the "/etc/paths.d" direc­tory on your system, which affects the system PATH vari­able. You can do this with the following one-line terminal command, which will ask you for your pass­word (again, substi­tute /YOUR/PATH/TO/bin with your actual path, and include the surrounding double quotes):

This command puts the path to Racket in a new file called /etc/paths.d/racket, which will be auto­mat­i­cally loaded in the future.

Testing path

To check that your PATH has been updated correctly, open a new terminal window and try echo $PATH again:

This time, you should see your Racket bin subdi­rec­tory at the end of the PATH list of direc­to­ries.

If so, you can now try which racket:

If that works, then you’re home free. Type racket and you should see some­thing like this:

If so, all is well. The > is the command prompt for Racket. Type ctrl+D or (exit) to quit Racket.