Re: [Dbmail-dev] daemonize

[Oleg Lapshin]

Hello

Paul J Stevens wrote:
> This is a long-standing issue. If anyone has any ideas I'd be happy to
> hear them.

perldoc -q daemon :

How do I fork a daemon process?

If by daemon process you mean one that's detached (disassociated from its 
tty), then the following process is reported to work on most Unixish systems.  

o   Open /dev/tty and use the TIOCNOTTY ioctl on it.  See tty for details.  Or
     better yet, you can just use the POSIX::setsid() function, so you don't
     have to worry about process groups.

o   Change directory to /

o   Reopen STDIN, STDOUT, and STDERR so they're not connected to the old tty.

o   Background yourself like this:

     fork && exit;


And this is Proc::Daemon module (I think, this help you):

sub Fork {
    my($pid);
    FORK: {
        if (defined($pid = fork)) {
            return $pid;
        } elsif ($! =~ /No more process/) {
            sleep 5;
            redo FORK;
        } else {
            croak "Can't fork: $!";
        }
    }
}
sub OpenMax {
    my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX );
    (!defined($openmax) || $openmax < 0) ? 64 : $openmax;
}

sub Init {
    my $oldmode = shift || 0;
    my($pid, $sess_id, $i);

    ## Fork and exit parent
    if ($pid = Fork) { exit 0; }

    ## Detach ourselves from the terminal
    croak "Cannot detach from controlling terminal"
        unless $sess_id = POSIX::setsid();

    ## Prevent possibility of acquiring a controling terminal
    if (!$oldmode) {
        $SIG{'HUP'} = 'IGNORE';
        if ($pid = Fork) { exit 0; }
    }

    ## Change working directory
    chdir "/";

    ## Clear file creation mask
    umask 0;

    ## Close open file descriptors
# May be close only STDIN STDOUT STDERR
    foreach $i (0 .. OpenMax) { POSIX::close($i); }

    ## Reopen stderr, stdout, stdin to /dev/null
    open(STDIN,  "+>/dev/null");
    open(STDOUT, "+>&STDIN");
    open(STDERR, "+>&STDIN");

    $oldmode ? $sess_id : 0;
}




> Marc Dirix wrote:
> > I've installed dbmail from svn over the debian rules script,
> >
> > The problem I think is, that one of the dbmail processes (lmtp or imap
> > I use both) doesn't completely detach from the console. Because after
> > starting dbmail from the init script I can't logout off the console
> > anymore.



-- 
Oleg Lapshin