build with specific sdk

gistfile1.txt

clang hi.c -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk -o hi

where -isysroot parameter is discovered with:

xcrun --sdk macosx10.9 --show-sdk-path

--sdk parameter possibilities:

thaddeus@pegasus:~$ xcodebuild -showsdks
OS X SDKs:
	OS X 10.9                     	-sdk macosx10.9
	OS X 10.10                    	-sdk macosx10.10

iOS SDKs:
	iOS 8.3                       	-sdk iphoneos8.3

iOS Simulator SDKs:
	Simulator - iOS 8.3           	-sdk iphonesimulator8.3