From: mfuhr@... (Michael Fuhr)
Date: 2004-12-27T08:52:01+09:00
Subject: Re: writing to unix socket

Roeland Moors <roelandmoors@telenet.be> writes:

> require 'socket'
> sock = Socket.new(Socket::PF_UNIX, Socket::SOCK_STREAM, 0)
> sock.connect(Socket::sockaddr_un(device))
> sock.puts('VERSION')
> sock.close
>
> This works sometimes, but sometimes it don't and then I get this
> error:
> test.rb:4:in `write': Broken pipe (Errno::EPIPE)
>         from test.rb:4:in `puts'
>         from test.rb:4

A write fails with EPIPE if the peer has already closed its side
of the connection.

> I can get it to work always if i put 'sleep 0.1' after
> connecting. But way do I have to do this. Is there a better
> method?

Using sleep to synchronize activities should be a warning that
something is wrong; if it works then it's more likely by accident
than by design.

What's on the other end of the connection?  If the peer closes its
side before you call puts() then you'll get EPIPE.  It's odd that
sleeping for 0.1 seconds apparently fixes the problem; I'd have to
think about it to see if I could contrive a situation where that
would happen.

What OS are you using?  Have you run a process trace on the peer
to see what it does after it accepts your connection?

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/