time(2) System Calls Manual time(2) time - (libc -lc) #include time_t time(time_t *_Nullable tloc); time() (Epoch) 1970-01-01 00:00:00 +0000 (UTC). tloc NULL tloc. . ((time_t) -1) errno . EOVERFLOW time_t. time_t 32- 64- 2038-01-19 03:14:08 UTC . time_t . EFAULT tloc ( ). time() C vdso(7) ( ) SIGSEGV. POSIX.1 . 4 100 400 . . Linux POSIX POSIX.1-2018 Rationale A.4.16. 2038 (ABIs) time_t 32 time_t(3type). C time() vdso(7). C11 POSIX.1-2024. SVr4, 4.3BSD, C89, POSIX.1-2001, V7. C errno . tloc NULL . tloc NULL . date(1), gettimeofday(2), ctime(3), ftime(3), time(7), vdso(7) 3 . . : . 6.18 8 2026 time(2)