posix_mkfifo Create a fifo special file (a named pipe) boolposix_mkfifo stringpathname intmode 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). ¬e.sm.uidcheck.dir;