Hi to all . I tried to make a simple and extensible skeleton ( sentinel.pl) , simple enough ( I'm new to perl), and extensible enough for me to be able to extend this script. The first task was to watch over two background scripts( greylister.pl, repeater.pl). It seems like daemon works, and death of any of background scripts is detectable for script, but one thing looks odd for me. Sentinel.pl is able to start greylister.pl\repeater.pl only if they weren't running at the moment of sentinel's first start, but if any of scripts will die later when sentinel.pl is running, this event is logged but scripts ( repeater\greylister) are not restarted.

#!/usr/bin/perl -w
# Watchdog daemon, made for watching and restarting of all system elem
+ents.
use warnings;
use POSIX;
use File::Pid;
use Proc::Background;
use POSIX qw(setsid);
use lib '/etc/squid/repeater/lib/HTTP';

my $daemonName    = "sentinel";
my $dieNow        = 0;
my $SleepMainLoop = 5;
my $logging       = 1;
my $logFilePath   = "/var/log/";
my $logFile       = $logFilePath . $daemonName . ".log";
my $pidFilePath   = "/var/run/";
my $pidFile       = $pidFilePath . $daemonName . ".pid";
my $greylister = Proc::Background->new('/etc/squid/all_ban.pl');
my $repeater = Proc::Background->new('/etc/squid/repeater/lib/repeater
+.pl');

chdir '/';
umask 0;
open STDIN,  '/dev/null'   or die "Can't read /dev/null: $!";
open STDOUT, '>>/dev/null' or die "Can't write to /dev/null: $!";
open STDERR, '>>/dev/null' or die "Can't write to /dev/null: $!";
defined( my $pid = fork ) or die "Can't fork: $!";
exit if $pid;

POSIX::setsid() or die "Can't start a new session.";
$SIG{INT} = $SIG{TERM} = $SIG{HUP} = \&signalHandler;
$SIG{PIPE} = 'ignore';
my $pidfile = File::Pid->new( { file => $pidFile, } );
$pidfile->write or die "Can't write PID file, /dev/null: $!";

if ($logging) {
    open LOG, ">>$logFile";
    print LOG "Sentinel started.\n";
    select((select(LOG), $|=1)[0]);
}

until ($dieNow) {
    sleep($SleepMainLoop);
        if (!$repeater->alive()) {
            logEntry ("Repeater isn't running, attempting to restart")
+;
           $repeater = Proc::Background->new('/etc/squid/repeater/lib/
+repeater.pl');

      }
if (!$greylister->alive()) {
                 logEntry ("Greyliter isn't running, attempting to res
+tart");
                 $greylister = Proc::Background->new('/etc/squid/all_b
+an.pl');
     }



}

sub logEntry {
    my ($logText) = @_;
    my ( $sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst )
+ = localtime(time);
    my $dateTime = sprintf "%4d-%02d-%02d %02d:%02d:%02d", $year + 190
+0, $mon + 1, $mday, $hour, $min, $sec;
if ($logging) {
    print LOG "$dateTime $logText\n";
    }
}


sub signalHandler {
    $dieNow = 1;
}

END {
if ($logging) { close LOG }
    $pidfile->remove if defined $pidfile;
}
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