$logfile=~/(.*)\.tar\.gz$/; 
        my $dirname=substr($1,0,-2);
[download]

If the match fails, that $1 will be wrong. Never use $1 unless it's in the conditional of the match test. I'd change those two lines to:

$logfile =~ /(.*)..\.tar.gz$/ or die "Bad non-match on $logfile";
my $dirname = $1;
[download]

Also, your "link/unlink" pair can be replaced by a simple "rename". They're equivalent under the hood, with a lot less duplication.

-- Randal L. Schwartz, Perl hacker