#!/usr/bin/perl
use strict;

my $cmd = "telnet";     # or talk
my $args = "testhost";  # or user
my $data = "my_name\nmy_pass\n\nstartup_cmd\n"; # or "hi user\n"

print "Running '$cmd' with '$args', and sending '$data'\n";

local $^F = 1000; # set max system file descriptor high!
pipe(READ,WRITE);
select((select(READ), $| = 1)[0]);

if (my $pid = fork) {
        # PARENT - launches the program
        #close(WRITE);
        # don't close the pipe, and '$cmd' doesn't die! :-)

        # One way, reopen stdin to the pipe:
        open(STDIN, "<&READ");
        exec "$cmd $args";

        # Another way, mess with file descriptors
        #   and shell redirection:
        #my $fd = fileno(READ);
        #print "fd = $fd\n";
        #exec "$cmd $args <&$fd";

        # similarly, try to grab STDIN as well:
        #exec "$cmd $args <&$fd &0<&$fd";
        # (however, seems to separate '$cmd' from the console)

        die "exec of '$cmd' failed.  $!";
} else {
        # CHILD - sends the data
        close(STDIN); close(STDOUT); close(STDERR); close(READ);
        print WRITE "$data\n";

        # Almost there, but instead of exiting, I need
        # to set WRITE back to the controlling console
        exit;
}