This is a simple echo server in Unix, using nc:
mkfifo fifo cat fifo | nc -k -l 4458 -v | cat >fifo
(based on this)
As I can see it, the data flow works as follows:
fifo (my named pipe) | | (using cat) | v nc | | (using cat) | v fifo
And here is the question: why doesn't this work?
nc -k -l 4458 -v >fifo <fifo
You will notice that if you try to
4458 you will get a "Connection refused" error.