Issue #2510 has been updated by Usaku NAKAMURA. additional information: to invoke native Windows child processes, xsystem returns true, but there is no output in mkmf.log except the names of invoked processes. to invoke cygwin processes, xsystem returns false. I think that ruby destroys stdout. And, starting of processes might fail for such case in cygwin. ---------------------------------------- http://redmine.ruby-lang.org/issues/show/2510 ---------------------------------------- http://redmine.ruby-lang.org