This is the first time I need to do fork , so Im reading and trying to learn how to do it.
Im reading and processing the log lines of my dhcp sever wich are coming really fast.
For each line I receive I need to perform a snmpget querie to the ips Im grabing.
The problem is that each querie takes more than a second to return a value so it is delaying all the script so I had to do fork.
I have this first version working but I would like have your opinion in order to improve it or make it run in a more secure way.
#!/usr/bin/perl -w
use strict;
use File::Tail;
use Cwd qw();
my $path = Cwd::cwd();

$SIG{'CHLD'} = "wait_for_child_to_die";

my $community='public';    
my $snmp_fver = '.1.3.6.1.4.1.2700.1.1.8.0';

my $file = File::Tail->new(
        name =>'/var/log/messages', 
        interval => 1, 
        maxinterval => 1, 
#        resetafter=> 5, 
        );

while (defined(my $line=$file->read)) {
         #print $line,"\n";
 
                if ($line =~ /^(.*) dns02cor dhcpd: DHCPACK on ([0-9\.
+]+) to ([[:xdigit:]:]+).* ([0-9\.]+)/) {
                unless (my $pid = fork) {
                die "Couldn't fork " unless defined $pid;
             
                write_register($1,$2,$3);  
                exit;
                }    
            }
}

sub write_register {
my ($date,$client_ip,$client_imsi) = @_;

 $output=qx(snmpwalk -v2c -t1 -c $community $client_ip $snmp_fver 2>&1
+);
 chomp($output);
        if( $output eq "Timeout: No Response from $client_ip" ) {
        return; 
        }
        else{
                   my @result=split(/:/,$output);
                   if ($result[3]){
           $fver=$result[3];
                   $fver=~s/ //g;
                   $fver=~s/\n//g;

                   }else{
            exit;
            }
               }

        if($bsid){
                system "sed -i '/$client_imsi/d' $path/leases_list.txt
+";
        system 'echo "'.$date.','.$client_ip.','.$client_imsi.','. $fv
+er.'" >> '.$path.'/leases_list.txt';
        }
        
}
sub wait_for_child_to_die
{
    wait;
}
1;

[download]

I must admint this is a mix of multiple scripts I founded on the web.
I hope to hear your opinion in case is there is something I should be aware or change.
I promess to read and learn about forking , wait , and related topics.
So far , it is not creating more than 8 process and no zombies also so Im very happy.
Regards,
Leandro.

In reply to Im I forking properly ? by leostereo

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