Talking to TCP server from shell

[Christophe De Troyer]

I have a pastebin clone that accepts content over a socket 
(https://github.com/m1dnight/exbin/blob/main/lib/exbin/socket.ex). The 
way you do it there is `echo "my content" | nc example.com 9999`.

I do recall that getting it to work was a bit of fiddling with the 
socket options..

Magnus Leone wrote on 11/12/2021 2:24 AM:
> Hello,
>
> I'm working on making a very basic talk about networking, and 
> eventually a webserver, but I thought I'd start with the very basic 
> parts; just a TCP echo server. The thing is that the talk is not 
> specifically about Erlang, I'm just using that as I'm most familiar 
> with it (and hey, if I get some people interested, that's great). So I 
> wanted the client side to be just a regular shell.
>
> Here is where my problem comes in - I can't seem to get the server 
> process to accept the incoming connection when it comes from a shell. 
> The code is pretty much straight out of Joe's book and it works fine 
> as long as the other side is also an Erlang process. What I've tried 
> so far:
>
> >telnet localhost 7777
> Trying 127.0.0.1...
> telnet: Unable to connect to remote host: Connection refused
>
> >netcat localhost 7777
> *no output*
>
> Does anyone know how I can use bash to connect to a TCP socket in this 
> scenario?
>
> Cheers,
> Magnus
>
> start(Port) ->
>     {ok, ListenSocket} =
>         gen_tcp:listen(Port, [list, {packet, 0},
>                                     {reuseaddr, true},
>                                     {active, true}]),
> {ok, Socket} = gen_tcp:accept(ListenSocket),
>     ok = gen_tcp:close(ListenSocket),
>     io:format("Server accepted connection on port ~p~n", [Port]),
>     loop(Socket).
>
> loop(Socket) ->
>     receive
>         {tcp, Socket, StringMsg} ->
>       io:format("Server received message: ~p~n", [StringMsg]),
>       Reply = "Echo " ++ StringMsg,
>             io:format("Server replying: ~p~n", [Reply]),
>             gen_tcp:send(Socket, Reply),
>           loop(Socket);
>         {tcp_closed, Socket} ->
>     io:format("Server socket closed - shutting down...~n")
>     end.

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