You’ve installed xcode and developer tools, but you moved xcode into a custom directory (maybe you have multiple versions).
Then let’s say you install something like homebrew.
Homebrew will tell you that it installed and you should run “brew doctor” before you install anything.
So you do and get this error:
Warning: Git could not be found in your PATH. Homebrew uses Git for several internal functions, and some formulae use Git checkouts instead of stable tarballs. You may want to install Git: brew install git xcrun: error: active developer path ("/Applications/xcode/6.0.1/Xcode.app/Contents/Developer") does not exist, use xcode-select to change
Well that’s because your system doesn’t know how to find the directory you just made and stuck your xcode app in (mine for example is buried in /Applications/xcode/6.1/Xcode.app)
That’s ok, see here: https://developer.apple.com/library/ios/technotes/tn2339/_index.html
Basically, you just need to run (this path is my installatino, adjust it accordingly…)
sudo xcode-select -switch /Applications/xcode/6.1/Xcode.app
To tell your system where to find things. Then everything runs perfectly, check it out!