Shell Programming and Scripting

#!/usr/bin/perl -w
use Error qw(:try);
use MIME::Base64;
use FindBin qw($Bin);
use POSIX qw(setsid setuid);
use Config::Auto;
use Proc::Daemon;
use Log::Log4perl qw(:easy);
use Platform;
use Platform::Queue;
use Platform::Video;
use strict;

# when we get a INT signal, set the exit flag
$SIG{INT} = sub { $::exit = 1 };

# setup logging
Log::Log4perl->easy_init($TRACE);

my ($log, $conf, $video, $sqs, $queue);

$log = Log::Log4perl->get_logger('aws-daemon');
$conf = Config::Auto::parse($Bin . "/aws.conf", format => "colon");
$video = Platform->new();
$sqs = Platform::Queue->new({
  aws_access_key_id     => $conf->{'aws_id'},
  aws_secret_access_key => $conf->{'aws_secret'} });

# fork into the background
# do this first because our process id will change
Proc::Daemon::Init;
$log->trace('calling daemonize()');
&daemonize();

# our infinite loop
while(1) {
  $log->trace('running...');
  exit if $::exit;
  check_queues($conf, $sqs, $video);
  $log->trace('sleeping for two minutes...');
  sleep(120);
  exit if $::exit;
  $log->trace('still running...');
}

sub check_queues {
  $log->trace('check_queues');
  my ($conf, $sqs, $video) = @_;

  try {
    $video->read_result_queue();
  } catch Error with {
    my $ex = shift;
    $log->trace('Exception in check_queues: ' . $ex);
  } finally {
  }
}

sub daemonize {
    chdir '/'                 or die "Can't chdir to /: $!";
    open STDIN, '/dev/null'   or die "Can't read /dev/null: $!";
    open STDOUT, '>>/tmp/awsd' or die "Can't write to /dev/null: $!";
    open STDERR, '>>/tmp/awsd' or die "Can't write to /dev/null: $!";
    defined(my $pid = fork)   or die "Can't fork: $!";
    exit if $pid;
    setsid                    or die "Can't start a new session: $!";
    umask 0;
}

   chdir '/'                 or die "Can't chdir to /: $!";
   open STDIN, '/dev/null'   or die "Can't read /dev/null: $!";
   open STDOUT, '>>/tmp/awsd' or die "Can't write to /tmp/awsd: $!";
   open STDERR, '>>/tmp/awsd' or die "Can't write to /tmp/awsd: $!";
   defined(my $pid = fork)   or die "Can't fork: $!";
#   exit if $pid;
   if ($pid)
   {
      print "stuff that is relevant to the process is output to screen"
      exit
   }
   setsid                    or die "Can't start a new session: $!";
   umask 0;

$ ps -ef | grep aws-daemon # Note the PID
$ kill -2 <pid of aws-daemon>

line 9#    use Platform;
line 10#   use Platform::Queue;
line 11#   use Platform::Video;