#!/usr/bin/perl -w

# http://poe.perl.org/?POE_Cookbook/Watching_Logs

use POE qw/Wheel::FollowTail/;
use strict;

$| = 1;

my $filename = $ARGV[0];

die "Usage: $0 <filename>\n"                     unless $filename;
die "$0: $filename: No such file or directory\n" unless -e $filename;
die "$0: $filename: Permission denied\n"         unless -r $filename;

POE::Session->create
  ( inline_states =>
      { _start => sub { $_[HEAP]->{wheel} =
              POE::Wheel::FollowTail->new(
                Filename   => $_[ARG0],
                InputEvent => 'got_line',
                ErrorEvent => 'got_error',
                SeekBack   => 1024,
              );
            $_[HEAP]->{first} = 0;
        },
        got_line => sub { print "$_[ARG0]\n" if $_[HEAP]->{first}++ },
        got_error => sub { warn "$_[ARG0]\n" },
      },
    args => [$filename],
  );

$poe_kernel->run();