posix_mkfifo() creates a special FIFO file which exists in the file system and acts as a bidirectional communication endpoint for processes.
The second parameter mode
has to be given in octal
notation (e.g. 0644). The permission of the newly created
FIFO also depends on the setting of the current
umask(). The permissions of the created file are (mode
& ~umask).
Returns TRUE on success or FALSE on failure.
Note: When safe mode is enabled, PHP checks whether the directory in which you are about to operate has the same UID (owner) as the script that is being executed.