after you fork, does the child process actually modify "my %kids" ?

...
my $pid = fork;
$pid == 0 and exec 'ping', '-c', '3', $site;
# child ($pid 0) never reaches code below.
# exec doesn't return, it can only exit
# or it can fail to find ping, but I use autodie
# (for this kind of program that's probably
# not a great idea in something
# that can be called 'production'... but w/e)

$kids{$pid} = $site; # only parent gets here
...
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I tried to do something similar with an array, but when I called it I got back a reference to an array. do you know why? (code is below)

foreach $element (@updevices){
        @ip = split(':',$element);
        die "Could not fork()\n" unless defined ($pid = fork);

        if ($pid) { push @pids, $pid; next;}
        # ^ this is parent code, it pushes $pid to array
        # and goes back to the top of the loop


        # below is child code
        # it does something and then exits
        system("ping $ip[2] 1 > /dev/null");
        $result = $?;
        print "ping $ip[0] $ip[2] $result\n";
        if ( $result !=  0)
        {
                print "$ip[0] is dead\n";
                push(@dead, $ip[0]);
        }
        exit; 
        # ^ child exits here
        # and basically stops (that's how exit works, after all)
        # and its exit code is 0; see perdoc -f exit
}
# after parent is done with the loop
# it continues here
# it has the array @pids
# and all other global vars that your script
# is full of...
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in your second loop, you wait for the kids to finish their process and print to stdout the actual return value, is this possible to track? for example I want to have this run all day so I'm thinking I could keep a hash that has these return values and times for tracking purposes

If not, then you probably should use signal handlers ($SIG{CHLD} specifically). See peripc.

thanks for the help, I did add additional exit codes in the my child processes and it solved my problems (I posted code below)

in the end, I figured the easiest way is for the parent to keep track of the children's exit status; because in the end that's all I care about.

I don't have access to "update" my version of perl (or add modules), but I'm definitely going to look more into the IPC, it really interests me.

foreach $element (@updevices)
{
        @ip = split(':',$element);
        die "Could not fork()\n" unless defined ($pid = fork);
        if ($pid) { push @pids, $pid; next;}
        system("ping $ip[2] 2 > /dev/null");
        $result = $?;
        if ( $result !=  0)
        {
                print "$ip[0] is dead\n";
                exit 1;
        }
        exit 0;

}

for $pid(@pids){
          waitpid $pid, 0;
          if ($? != 0)
          {
             $i++;
          }
}

print "$i dead devices\n";
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Oh, I see. You were probably asking about the array @dead. I didn't notice it (that's why it's a good idea to use strict and declare all variables). Yeah, parent cannot use @dead because after fork parent and child are two completely different processes and don't share variables (actually, parent can use @dead but it just will be empty).