POSIX = Portable Operating System Interface. 만약 Linx 계열 OS가 "POSIX compliant" 가 되려면, 아래와 같은 required header 들을 반드시 포함해야 한다. POSIX.1 : IEEE 1003.1 1990 edition ~ IEEE 1003.1 2008 edition Required Headers defined by the ISO C Standard Headers Description assert.h verify program assertion complex.h complex arithmetic support ctype.h character classification and mapping support errno.h error codes f..