Just as a side node and because TMTOWTDI, I do such tests like this:

$name = ..... # whatever
my $i= '';
--$i while (-e $name . $i);
$name.= $i;
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Of course this will give you -1 instead of _1.

Did you notice that your "_1" is appended to the ".html"? You don't get 07141998_1.html but 07141998.html_1. For demonstration purposes, mine isn't better here.

A fix could be TMTOWTDI:

my $check= $name;
$check=~ s#(\.[^./]*)$##;
my $ext= $1 || '';
my $i= '';
--$i while (-e $check . $i . $ext);
$name= $check . $i . $ext;
[download]