I have a loop waiting for 'y', which works well. However, when i run it via telnet (and xinetd), it does not:

$| = 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
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So, this is obviously because of telnet. But why is the file empty until a chomp, and \r instead of \n afterward?

-------------------------

UPDATE 10/31/11:

Following http://www.perlmonks.org/?node_id=549385, i found $/ set to \n, telnet sends \r\n. chomp removed the \n, but not the \r, hence it never matched.

As to why /moo1 is empty, i do not know, but it's interesting.

To test, here is a simple script:

#!/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";
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To use xinetd, add an entry to /etc/services:

test 4217/tcp

And add a file to the /etc/xinetd.d directory (at least on Debian) with the following contents:

service test
{
        disable         = no
        socket_type     = stream
        wait            = no
        user            = chacham
        server          = /home/chacham/test.pl
}
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To execute: telnet localhost 4217 ; od -c /tmp/moo;

Removing while(1) or last..., uncommenting the unpack, or making write >, append >>, makes it fill moo with the data.