mkfifo

Make FIFOs (named pipes)
Creates the fifos requested, in the order specified, using mode 0666 modified by the current umask.

Syntax
       mkfifo [-m mode] fifo_name ...

Options
  -m      Set the file permission bits of newly-created
          directories to mode. The mode is specified as in chmod.

          In symbolic mode strings, the `+' and `-' operators
          are interpreted relative to an assumed initial mode of `a=rw'

mkfifo requires write permission in the parent directory.
mkfifo exits 0 if successful, and >0 if an error occurred.

A "FIFO" is a special file type that permits independent processes to communicate. One process opens the FIFO file for writing, and another for reading, after which data can flow as with the usual anonymous pipe in shells or elsewhere.

"Ceci n'est pas une pipe" (This is not a pipe) - Magritte

Related:

mkfifo man page - Apple.com
mknod - Make block or character special files
sed - Stream Editor
umask - Users file creation mask