The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
POSIX_F_OK
     (integer)
   POSIX_R_OK
     (integer)
   POSIX_W_OK
     (integer)
   POSIX_X_OK
     (integer)
   POSIX_S_IFBLK
     (integer)
   POSIX_S_IFCHR
     (integer)
   POSIX_S_IFIFO
     (integer)
   POSIX_S_IFREG
     (integer)
   POSIX_S_IFSOCK
     (integer)
   Note:
These constants are available since PHP 5.1.0. Please also note that some of them may not be available in your system.