after I upgrade the xcode from 7.1 to 7.1.1 then the command line tools have problem, detail is:
sh: line 1: 5268 Segmentation fault: 11 /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -sdk iphoneos -find clang 2> /dev/null
xcrun: error: unable to find utility "clang", not a developer tool or in PATH
at the same time in /Application/Xcode.app/Contents/Developer/usr/bin, there isn't clang and clang++, but it exist in the /usr/bin/