Is it possible to use xcodebuild on linux?
You can't use the standard Apple developer tools on Linux, because they're compiled for Mac OS X.
If you're compiling for iOS, you can, however, build an opensource iOS toolchain for linux and use it for compiling your app. You'll need a jailbroken device to upload the binary, though.
If you're working with a normal OS X application, then, provided you have the necessary libraries and frameworks, you can build the project for Linux using make.