Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: IPC Servers
Keywords: IPC server perl
Message-ID: <7036@jpl-devvax.JPL.NASA.GOV>
Date: 9 Feb 90 16:52:49 GMT
References: <1328@gapprd.gapos.bt.co.uk>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 33

In article <1328@gapprd.gapos.bt.co.uk> steve@gapos.bt.co.uk (Steve A Rooke) writes:
: As a novice perl hacker (of a few days) I have been looking at the
: interprocess communication and want to set up a server that will start
: up a unix executable and attach it to the pipe for the duration of the
: session and when finished the server will start `listening again'.
: I see there is a command `select' that I can change stdout to the socket
: file handle but I can not find the command to change stdin in the same 
: way.

Select isn't doing what you think it's doing.

What you want is probably

	socket(SOCK, ...);
	bind(SOCK, ...);
	listen(SOCK, 5);
	accept(NSOCK, SOCK);

	$pid = fork;
	if (!$pid) {
	    open(STDIN, "<&NSOCK");
	    open(STDOUT,">&NSOCK");

	    close NSOCK;
	    close SOCK;
	    exec '/usr/lib/sendmail', '-bs';	# or whatever
	}
	$status = wait;
	...

Or some such.

Larry