#!/usr/bin/perl -w
use strict;
use IO::Socket;
use Sys::Hostname;
use POSIX qw(:sys_wait_h);
sub REAP {
    1 until (-1 == waitpid(-1, WNOHANG));
    $SIG{CHLD} = \&REAP;
}
$SIG{CHLD} = \&REAP;
my $sock = new IO::Socket::INET(
                   LocalHost => '127.0.0.1',
                   LocalPort => 9898,
                   Proto     => 'tcp',
                   Listen    => 10,
                   Reuse     => 1);
$sock or die "no socket :$!";
STDOUT->autoflush(1);
STDERR->autoflush(1);
my($new_sock, $buf, $kid);
print STDERR "Parent $$: Server up\n";
while ($new_sock = $sock->accept()) {
    next if $kid = fork;
    die "fork: $!" unless defined $kid;

    # child now...
    print STDERR "Child $$\n";

    # close the passive socket - not needed
    $sock->shutdown(2);

    # read from client
    $buf = <$new_sock>;
    $new_sock->shutdown(0);
    chomp $buf;
    print "Child $$: Read from client: $buf\n";
        print $new_sock "READY\n";
    print "Child $$: Sent READY, closing\n";
        $new_sock->shutdown(2);
    exit;
} continue {
    # parent closes the client since
    # it is not needed
    print STDERR "Parent $$: Closing child socket\n";
    close $new_sock;
}


print STDERR "Parent $$: Should never get here\n";

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use IO::Socket;

my $me = 'some_client';

my $socket = IO::Socket::INET->new( PeerAddr    => '127.0.0.1',
                    PeerPort    => '9898',
                    Proto       => 'tcp',
                    Type        => SOCK_STREAM )
    or die "Couldn't connect to 127.0.0.1:9898: $@\n";

$socket->autoflush(1);

print $socket "$me $$\n";

# no more writing from here
$socket->shutdown(1);

my $line = <$socket>;
chomp $line;
print STDOUT "$line\n";
$socket->close;

exit 1 unless $line eq 'SUCCESS';
exit 0;


##</code><code>##

Parent 11124: Server up
Parent 11124: Closing child socket
Child 11131
Parent 11124: Should never get here
Child 11131: Read from client: some_client 11130
Child 11131: Sent READY, closing