I'm trying to learn the fork() command by applying it in a simple "multi-copy" command script.
It somewhat works until, I believe, it reaches the last pid. I get an error "The instruction at ####### referenced memory at #######. The memory could not be read." I don't know why. Can someone help?

Here's a snippet of the code used: 
$| = 1; # turn off buffering
my $pid = $$; # $$ holds the current process ID number
my $parent = 0; # the original process was an immaculate conception
my @kids = (); # no babies yet
 
FORKER: for ($i = 1; $i <= $threads; $i++){
    my $newpid = fork();
    if ( not defined $newpid ){
        # if return value of fork() is undef, something went wrong
        die "fork didn't work: $!\n";
    }elsif ( $newpid == 0 ){
        # if return value is 0, this is the child process
        $parent = $pid; # which has a parent called $pid
        $pid = $$; # and which will have a new process ID number of it
+s very own
        @kids = (); # the child doesn't want this baggage from the par
+ent
        last FORKER; # and we don't want the child making babies eithe
+r
    }else{
        # the parent process is returned the PID of the newborn by for
+k()
        logentry("$$ spawned $newpid",$log_file);
        push @kids, $newpid;
    }
}
if ( $parent ){ # if I have a parent, i.e. if I'm the child process
    do_something();
    exit( 0 );
}else{
    # parent process needs to preside over the death of its kids
    while ( my $kid = shift @kids ){
        logentry("Parent waiting for $kid to die",$log_file);
        my $reaped = waitpid( $kid, 0 );
        unless ( $reaped == $kid ){
            logentry("Something's up: $?",$log_file);
        }
    }
}
 
sub do_something {
    $offset = 0;
    if ($i == $threads){
        $offset = $num_of_files - ($threads*$per_batch);
    }
    $start_point = (($i-1)*$per_batch)+1;
    $end_point = $i*$per_batch + $offset;
    for ($ii = $start_point; $ii <= $end_point; $ii++) {
        if (!$testmode){
            copy "$list[$ii-1]" => "$target";
        }
        logentry("copying $list[$ii-1] => $target",$log_file);
    }
    return(1);
}

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regards
Sacco

In reply to forking memory problem by sacco

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