posix_mkfifo() creates a special FIFO file which exists in the file system and acts as a bidirectional communication endpoint for processes.
pathnamePath to the FIFO file.
mode
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).
Note: When safe mode is enabled, PHP checks whether the files or directories you are about to operate on have the same UID (owner) as the script that is being executed.