• you do a Perl 'open' on the file
• you then do a Unix redirect to the file (which perl now has open - dangerous)
• your Unix redirect doesn't append, it overwrites - you need a '>>' instead of a '>' before 'pingall.list' in your system call
• then you don't close the file before opening it for read. This is not strictly a bad thing, but you should do this for neatness sake

So, what I think is happening is that Perl has the file open, then you use system calls to write to it. Then you do the second Perl open, which causes perl to flush out what it thinks should be in the file (which is nothing) and so you land up with an empty file.

check out Net::Ping for an easier way to do the pinging

I made some changes but continue to get the same output, 'ERROR'. I know my code was kinda messy and i tried to clean it up by closing all the filehandles before reopening them and a few other changes. Heres what I have:

# Create a list of all possible IP addresses within subnet
open(ALLIP, ">allip.list") || die "Unable to create file: allip.list\n
+";
for ($i=0; $i<=20; $i++) {
        print ALLIP "$ip_subnet.$i\n";
}
close(ALLIP);
open(ALLIP, "allip.list") || die "Unable to open file: allip.list\n";
open(PINGALLIP, ">pingallip.list") || die "Unable to open file: pingal
+lip.list";
while (<ALLIP>) {
        system("ping $_ >pingallip.list") && "Unable to create file: p
+ingallip.l
ist";
chomp; }
close(ALLIP);
close(PINGALLIP);
open(OUTPUT, ">output.list");
open(PINGALLIP, "pingallip.list") || die "Unable to open file: pingall
+ip.list";
my $line = 0;
while (<PINGALLIP>) {
chomp;
        if ($_ =~ m/is alive/) {
                $line++;
                last;
        }

}
close(PINGALLIP);
        if ($line) {
                print OUTPUT "$_\n";
        } else {
                print "ERROR\n";
        }
[download]

Any more help would be greatly appreciated. ~_^

~Zuinc

open(ALLIP, "allip.list") || die "Unable to open file: allip.list\n";
while (<ALLIP>) {
        chomp;
        system("ping $_ >>pingallip.list");
}
[download]

You know of course that you can perform pings from Perl with Net::Ping? The script does have to be setuid root, though, if you want to use ICMP packets (if this means nothing to you, then you do want to be using them).

If the IP addresses of the machine you are pinging are within a single network, you might be interested in a script I posted a while back: pinger - ping a range of hosts. There may be some ideas you can use.

 if ($_ eq~ m/is alive/) {
                $line++;
                last;
        }

should be =~

So, apart from that, what happens when you try running it under the debugger?

--t. alex

"Here's the chocolates, and here's the flowers. Now how 'bout it, widder hen, will ya marry me?" --Foghorn Leghorn