By default socat open a separate r/w channel for each specified address,
and terminates the connection after .5s from receiving EOF on _either_
side. And since one side of that connection is an empty stdin, we reach
that EOF pretty quickly. Let's avoid this by using socat in
"reversed unidirectional" mode, where the first address is used only for
writing, and the second one is used only for reading.
Addresses:
- https://github.com/systemd/systemd/issues/31500
- https://github.com/systemd/systemd/issues/31493
Follow-up for 3456c89ac2.
Frantisek Sumsal
Yu Watanabe
Lennart Poettering