Open Clion from terminal

Start CLion using the GUI interface, then start Terminal and run the following to find what process is running:

ps -ae| grep lion

Output

57257 ??         0:20.45 /Applications/CLion.app/Contents/MacOS/clion
57434 ttys000    0:00.00 grep lion

So the command I need to use, in my case, to start CLion from the command line is:

/Applications/CLion.app/Contents/MacOS/clion

Then you need to pass the directory containing your project, so you could make a function like this:

function CLion {  /Applications/CLion.app/Contents/MacOS/clion "$1"; }

Then you can just type:

Clion ~/CLionProjects/someProject

In researching this question, I just discovered that there is an officially supported method for doing this is via CLion's Tools|Create Command Line Launcher... menu item.

Full details are posted here: https://www.jetbrains.com/help/clion/working-with-the-ide-features-from-command-line.html