open my $infile, "<", "test.txt" or die "cannot open input: $!"; my @infile1= <$infile>; close $infile; foreach my $dns ( @infile1 ) { chomp $dns; if ($dns =~ /(dns:[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})$/){ my ($ip, $dns1) = split /dns:/, $dns; ($ip) = split /,/, $dns1; print "$ip";} }