Here are more informations to save you the time searching for it. Introduced in f095bb7 (2010-01-09) in stdlib/stdlib.h line 609: +#if defined __USE_MISC || defined __USE_XOPEN_EXTENDED \ + || defined __USE_XOPEN2K8 [..] extern int mkstemp (char *__template) __nonnull ((1)) __wur; And in include/features.h (from glibc 2.12 e28c887): #if (_POSIX_C_SOURCE - 0) >= 200112L # define __USE_XOPEN2K 1 # undef __USE_ISOC95 # define __USE_ISOC95 1 # undef __USE_ISOC99 # define __USE_ISOC99 1 #endif #if (_POSIX_C_SOURCE - 0) >= 200809L # define __USE_XOPEN2K8 1 # undef _ATFILE_SOURCE # define _ATFILE_SOURCE 1 #endif -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html