change:

while (<PINGALLIP>) {
   if (/is alive/) {
                chomp;
                print ALIVEIP $_;
        }
}
[download]

to:

while (<PINGALLIP>) {
   if ($_ =~ /is alive/) {
                chomp;
                print ALIVEIP $_;
        }
}
[download]

That will apply the m// operator to magic variable $_, which is the current line of your while loop.