I use the following, which seems to work well (though results in some horribly long file names).

my $outfile = localtime;
print "$outfile\n";
$outfile=~s/\s|://g;
$outfile="$outfile" . rand($outfile);
$outfile=~s/\.//g; #for win32 - doesn't like multiple dots
print $outfile;
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