#!/usr/bin/perl 
                                                                                                  
# daemon.pl

use POSIX qw(setsid);
use IO::All;
use strict;
use warnings;

daemonize();

my $date_time;

while (1) {
   $date_time = scalar localtime;
   qq($date_time\n) > io('/tmp/daemon.log');
   sleep 5;
}

sub daemonize {
   defined (my $child = fork) or die qq(I really can't do that...!\n);
   exit if ( $child );
   setsid();
   open( STDIN, "</dev/null" ); 
   # open( STOUT, ">/dev/null" );  # inferior mistake!    
   open( STDOUT, ">/dev/null" );                                                                    
   open( STDIN, ">&STDOUT" );
   chdir '/';
   umask(0);
   # ENV{PATH} = qq(what/you/really/need);                                                                        
}

__END__

##</code><code>##

tail -f /tmp/daemon.log

##</code><code>##

# ps aux | grep '[/]usr/bin/perl ./daemon.pl' | perl -ane 'print $F[1]';
# if many...
ps aux | grep '[/]usr/bin/perl ./daemon.pl' | perl -ane 'print $F[1] . qq(\n)'

##</code><code>##

# kill -TERM $(ps aux | grep '[/]usr/bin/perl ./daemon.pl' | perl -ane 'print $F[1]';)
# if many...

kill -TERM $(ps aux | grep '[/]usr/bin/perl ./daemon.pl' | perl -ane 'print $F[1] . qq(\n)')