xcrun: Error: failed to exec real xcrun. (No such file or directory)

I had the same problem. Originally I was doing the following for my xcode-switch:

$ sudo xcode-select -switch /Applications/Xcode.app/

However what was really needed was:

$ sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/

This fixed the problem for me. Not sure if sudo is needed.

The only fix is hack apparently. I tried the script mentioned and it worked

OSX 10.8 xcrun (No such file or directory)