$| = 1;

 while (1)
 {
     $_ = <>;
     open FILE, ">/tmp/moo1"; print FILE $_; close FILE;
     chomp;
     open FILE, ">/tmp/moo2"; print FILE $_; close FILE;
     last if $_ eq "y";
 }

Checking the files:

> od -c /tmp/moo1
0000000
> od -c /tmp/moo2
0000000   y  \r
0000002

##</code><code>##

#!/usr/bin/perl -w

use strict;

# for telnet, turn off buffering.
$| = 1;

while (1)
{
    print "? ";
    $_ = <>;
    #print(unpack('H*', $_), "\n");
    print $_;
    open FILE, ">/tmp/moo"; print FILE $_; close FILE;
    last if $_ eq "y";
 }

print "\n";

##</code><code>##

service test
{
        disable         = no
        socket_type     = stream
        wait            = no
        user            = chacham
        server          = /home/chacham/test.pl
}