Verify that you've successfully installed Xcode Command Line Tools:
mokin.li@MoKinLiMacBook-Pro ~ % xcode-select -p
/Library/Developer/CommandLineTools
mokin.li@MoKinLiMacBook-Pro ~ %
Verify that you've successfully installed Xcode Command Line Tools:
mokin.li@MoKinLiMacBook-Pro ~ % xcode-select -p
/Library/Developer/CommandLineTools
mokin.li@MoKinLiMacBook-Pro ~ %