预定义常量
PHP Manual

posix_mknod() constants

Note:

These constants are available starting with PHP 5.1.0. Please note that some of them may not be available on your system.

POSIX_S_IFBLK (integer)
Block special file
POSIX_S_IFCHR (integer)
Character special file
POSIX_S_IFIFO (integer)
FIFO (named pipe) special file
POSIX_S_IFREG (integer)
Normal file
POSIX_S_IFSOCK (integer)
Socket

预定义常量
PHP Manual