Hi folks,

How would I be able to write to the opened binary process in the child process from the parent
process in the else block. Should I share/reference the SREAD and SWRITE handles between both
the child and parent ? And how would I do that (without opening the handles globally) !?

I also need to be able to monitor the state of the binary process that I have spawned, that's why I have used open2(),
because it returns a PID that I can use waitpid() on and re-load the binary when it has terminated.
But at the same time, I also need to be able to write to the binary process. That's why I have separated both tasks with fork().
Maybe you think that what I am doing should/could be done differently ? Got any ideas ?

It's too damned hot. I need a cold glass of water ...

Update: PS --- All processes MUST be daemons/run in the background 

use strict;
use POSIX qw(setgid setuid);
use IPC::Open2;

my $got_sig=0;

$SIG{'TERM'}=\&catch_sig;
$SIG{'INT'}=\&catch_sig;
$SIG{'HUP'}=\&catch_sig;
$SIG{'QUIT'}=\&catch_sig;
$SIG{'ABRT'}=\&catch_sig;

sub catch_sig {
    $got_sig=1;
}

# Set UID & GID
my $uid = xxx;
my $gid = xxx;

# Set GID before UID so that we can still call setuid().
setgid $uid;
setuid $gid;

my $program = "/path/to/some/binary";
my $actual_prog = "file_name_of_binary";
my @prog_opts = "some_sort_of_arguments";

# GMT offset needs to be changed accordingly in Daylight 
# Savings periods : Cause I am lazy ...

my $gmt_offset = 8;
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday)
   = gmtime(time);
my $zone_standard_hour = ($hour + $gmt_offset);
my $actual_year = ($year + 1900);
my $actual_mon = ($mon+1);
my $actual_standard_time = "$zone_standard_hour$min$sec-$mday-$actual_
+mon-$actual_year";
my $logfile = "/absolute/path/of/logfile/logs/$actual_standard_time-se
+rver.log";


###################################################
# FORGET ABOUT ANYTHING ABOVE HERE. READ BELOW !!!#
###################################################

my $spid;
print "Launching \"$actual_prog\" as UID($uid)/GID($gid)\n";

unless(my $ppid=fork()) {
    if (!(my $pid=fork())) {
        # Child
        while(1) {
            open(STDERR,">> $logfile");
            $spid = open2('SREAD', 'SWRITE', "$program @prog_opts");
            waitpid($spid,'WNOHANG');
            print STDOUT "Server \"$actual_prog\" exited. Re-load!\n";
       }
    }else{
       # Parent
       while(1) {
            if($got_sig==1) {
                print STDOUT "Closing up shop ...\n";
                kill('KILL',$spid);
                exit(0);
            }else{
                sleep 5;
                print SWRITE "Blah blah blah\n" 
                or print STDOUT "No good, sunny boy !\n";
            }
        }
    }
}

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In reply to Shared file-handles & fork fun by kabeldag

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