$SIG{HUP} = sub { exec($0, @ARGV); };

##</code><code>##

#!/usr/local/bin/perl
use strict;
use vars qw($hup);

$| = 1;
$hup = 0;

$SIG{HUP} = sub { $hup++; };   # handle the hup when convenient

print "\n$0: args @ARGV, pid $$...\n";
while (1) {
  print "grinding away...\n";
  sleep(5);
  if ($hup > 0) { exec($0, @ARGV) || warn "$!"; }
}