xcode - Invalid active developer path on MAC OS X after installing Ruby

Question

I get this error:

xcrun: error: invalid active developer path (/Applications/Xcode.app), missing xcrun at: /Applications/Xcode.app/usr/bin/xcrun

This solution works, but the error occurs again after closing my terminal and reopening it; I then have to run the same commands every time I open a new terminal window.

How can I apply these changes such that they will save after closing the terminal window out?

Answer 1

I started getting the same error after updating to OS X El Capitan.
In my case, all I did was to install it:

sudo xcode-select --install

And it works fine for me.