Lincoln Stein covers the basics for Unix in Chapter 10, Forking Servers and the inetd Daemon, and Chapter 14, Bulletproofing Servers, in Network Programming with Perl.

There's a bit more to being a well-behaved daemon than is obvious at first glance. On page 312, Stein notes that a well-behaved daemon should:

1. "Autobackground" itself (fork/parent-exit), then close file handles and lose any assocition with a controlling terminal.
2. Change the current working directory to a known directory.
3. Change the file creation mask to a known state.
4. Set the PATH to a known state.
5. Record its process ID in a known place
6. Optionally use syslog to write diagnostics
7. Optionally handle HUP signals (e.g. to reload configuration files)
8. Options use chroot()

I've been quite impressed with Net::Daemon so far. It does most of what you listed there right out of the box and appears to be quite portable (though admittedly I have not tried to run it under windows).

-Matt

If you're asking if you're on the right track, I think so. In theory, one would start it via /etc/init.d in Linux and the system services in Windows, just as you say.

Do you have a more specific question? It's difficult to understand exactly what you're asking as you seem to have answered yourself quite nicely.

Lets assume the following piece of code:

#/usr/bin/perl -w
use strict;

my $count = 0;
while (1) {
 open(FILE,"filename.txt");
 print FILE "$count - \n";
 close(FILE);
 sleep(100);
 count++;
}
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If i wanted that piece of code to run at startup, does anything special need to be done with it, to run it from /etc/init.d

If the init script is as follows (cut down for example purposes):

case "$1" in
  start)
    daemon /usr/local/bin/myscript.pl
        ;;
  stop)
    #stop stuff here
        ;;
esac
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perldoc perlipc has a section on creating daemon processes (for UNIX).
For Windows, you may not need to do anything special other than adding the script as a service but I'm no Windows expert.

Hope this helps.

--perlplexer

I'm afraid you will have to test the value of $^O and load some OS specific modules or define some subroutines. I can't comment on the Unix side, but you might end up with something like:

BEGIN {
  if ($^O eq 'MSWin32') {
    eval <<'*END*';
      use Win32::Daemon::Simple 
        Service => 'SERVICENAME',
        Name => 'SERVICE NAME',
        Version => 'x.x',
        Info => {
          display =>  'SERVICEDISPLAYNAME',
          description => 'SERVICEDESCRIPTION',
        },
        Params => {};
*END*
    die $@ if $@;
  } else {
    eval <<'*END*';
      # do whatever you need to make it a daemon under Unix

      sub DoEvents {
        # check the value of the variable you set in $SIG{...} handler
+s 
        # and stop if asked to
      }
*END*
    die $@ if $@;
  }
}

while (1) {
  # do something
  sleep(60);
  DoEvents();
}
__END__
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Jenda
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
   -- Rick Osborne

Edit by castaway: Closed small tag in signature