How to capture UDP traffic so it can be piped to grep

Question

I'm trying to capture UDP traffic which is being sent as StatsD metrics (on port 8125).

The most simple approach I tried is to run nc -ul 8125 which prints the metrics to the terminal...but they are not newline separated. Additionally, piping the output to grep doesn't display anything.

The next approach I tried was socat - udp-listen:8125 which gives similar results to netcat.

However, when I pass in the -v flat and pipe stderr to stdout, (socat -v - udp-listen:8125 2> &1 | grep ...) then I get vaguely decent results but there's lots of additional unwanted output.

I also tried tshark, tshark -l -f "port 8125" -i ln0 -E separator=, -Tfields -e data but this prints the output as hexadecimal...not ascii. I can pass in the -x flag, which prints both the hex and the ascii side by side. Not really what I want, and not very grep friendly. I've also tried a bunch of other tshark options, but nothing was able to simply print the UDP metrics.

I have seen some examples where somebody doing something similar is pipling output like | while read output; do echo $output; done; However, I've not had any success with that approach and I'm not really a unix guy so I'm struggling to come up with a solution.

After all, it doesn't seem like such a uncommon task, and nc -ul 8125 is almost there....

To give more context...the code doing the sending looks like this:

var udpClient = new UdpClient();
udpClient.Connect("127.1", 9999);
while (true)
{
    var bytes = Encoding.UTF8.GetBytes("hi");
    udpClient.Send(bytes, bytes.Length);
    Thread.Sleep(1000);
}

the desired output would look like

hi
hi
hi
...

whereas nc -ul 9999 outputs hihihihihi....

Answer 1

socat -u UDP-RECVFROM:8125,fork SYSTEM:"sed G"

This seems to work although there is a bit more than just new line attached. Also maybe this thread can help: https://unix.stackexchange.com/questions/458951/how-can-i-add-message-delimiters-to-a-udp-stream-socat-is-piping

To expand why sed G works... sed has two "spaces" pattern space and hold space. sed G basically takes what's in the pattern space and adds newline to it. In this case the pattern space is empty so it effectively just adds a new line.