Don't forget to close STDIN, STDOUT and STDERR, and change pwd to "/" so you don't end up with a background process keeping you from unmounting some filesystem later on. I use the following at daemon start time.

my $pid = fork();

if($pid != 0){
    exit 0;
}

chdir "/";

close STDOUT;
close STDERR;
close STDIN;

POSIX::setsid();   # this takes care of controlling terminals
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Stevens covered this pretty well, I think it was "Advanced Programming in the UNIX Environment" or some such.