_POSIX_VERSION: 200809
NULL: (nil)
R_OK: 4
W_OK: 2
X_OK: 1
F_OK: 0
SEEK_SET: 0
SEEK_CUR: 1
SEEK_END: 2
F_LOCK: 1
F_ULOCK: 0
F_TEST: 3
F_TLOCK: 2
STDIN_FILENO: 0
STDOUT_FILENO: 1
STDERR_FILENO: 2