mac osx up brew xcrun: error: invalid active developer path

Q:

[root@localhost ~]$ brew install git
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), 
missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
Error: Failure while executing: git config --local --replace-all homebrew.private true

A:

 xcode-select --install

Then, continue:

sudo xcode-select -switch /