This question already has an answer here:
When we run this with a POSIX shell,
$ cmd0 | cmd1
STDOUT of cmd0 is piped to STDIN of cmd1.
Q: On top of this, how can I also pipe STDOUT of cmd1 to STDIN of cmd0?
Is it mandatory to use redirect from/into a named pipe (FIFO) ? I don't like named pipes very much because they occupy some filesystem paths and I need to worry about name collisions. Or do I have to call pipe(2) via C, Python or some general purpose programming languages?
(Both cmd0 and cmd1 do some network I/O, so they won't block each other forever.)