How can I send a UDP packet from bash and receive the response

Question

I want to send a UDP packet from bash (perhaps using netcat or socat) and then receive the one-packet reply, or time-out after three seconds.

(Strictly, the listening needs to start before the initial packet is sent.)

Is this possible, or do I need to write my own small C program?

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• Netcat lets me either send or receive, so it won't do the job.
• Likewise for socat.
• Perhaps there is already a UDP request/response tool, but I don't know how to find it.

I need to write my own program for this use case.

Answer 1

Socats datagram mode works asynchronously. In particular, something like

socat -t 3 - UDP-DATAGRAM:localhost:7777,bind=:6666

might come near your requirements.