hmm, Just notice that, thanks..

I think, .* and .{0,} at the beginning of a regex pattern shold have been treated as optional, so that /.*A/ and /.{0,}A/ should be the same as /A/ which means .* and .{0,} are completely unnecessary in the above patterns..

But \z looks behave very differently to .* and .{0,} as you mentioned.

This looks like a Perl-related problem, PHP(use a similar regex engine) does it pretty well:

php -r '
  $str = "foo\n"; 
  if (preg_match("/.*\z/", $str)) { 
    print "match\n";
  }
'
match
[download]

Probably it's a bug, and I am waiting for someone to make it clear. :-)

Regards,
Xicheng