GNU Screen vs. Socat – Comparison

Ok, I think at least I got something with socat - namely, the option fork needs to be appended to the server line:

$ socat - udp4-listen:5000,reuseaddr,fork

... and then, in another terminal, we can call echo piping into socat client line multiple times on command line, as it will exit immediately (well, after half a second :)):

$ echo "hello" | socat - udp-sendto:127.0.0.1:5000
$ echo "hello" | socat - udp-sendto:127.0.0.1:5000
$ echo "hello" | socat - udp-sendto:127.0.0.1:5000

... and going back to the first terminal, we can see that the server has successfully shown all three hellos:

$ socat - udp4-listen:5000,reuseaddr,fork
hello
hello
hello
^C

Note that even with a fork-ed socat server, the line echo "hello" | nc -u 127.0.0.1 5000 will still 'lock' as if waiting for user input; however, now after Ctrl-C and re-running the command, i.e.

$ echo "hello" | nc -u 127.0.0.1 5000
^C
$ echo "hello" | nc -u 127.0.0.1 5000
^C
$ echo "hello" | nc -u 127.0.0.1 5000
^C

... the fork-ed socat server will show three hellos without the need to be restarted..

Seemingly, this openBSD netcat doesn't have a fork option - but I'm not sure if it has one that is corresponding to it..

Anyways, hope this helps someone,
Cheers!

This comes straight from the Wikipedia page on netcat. In Term3, you would run:

mkfifo backpipe
nc localhost 55545 0<backpipe | nc localhost 55546 1>backpipe

This does pretty much exactly what you want. It uses a FIFO to get output from the left-hand side back into the right-hand side. It's not, strictly speaking, a temporary file -- a FIFO is a named pipe between two processes.