It is freezing here in Chicago, I would take Australia in a NY minute.

Robbin

As we’ve discussed privately - context is *everything*.

If your website only ever has a single level directory tree, there is no problem.
If you don’t care about intervening directories - ditto.

When I’m trying out a more complex RegEx, I’ll usually create a small set (10-20) of test cases to see what matches and what doesn’t. Try and cover all possibilities of what should and shouldn’t match, and see if I got it right. I usually don’t.

So for your original case I’d try:

/mypage/index.htm (Y)
/mypage/index.html (N)
/MyPage/Index.HTM (Y?)
/otherpage/index.htm (N)
/mypage/other.htm (Y)
mypage/other.htm (N)
other.htm (N)
other.gif (N)
/mypage/index.jpg (N)
/mypage/lower/index.htm (N?)
/mypage (N)
/mypage/ (N)
/mypage/htm (N)

/mypage/index.htm?id=1234 (N, but should it?)

where the bracketed Y or N is not included in the test data, but shows what I’d expect to see match or not.
Some of these are self evident “Won’t Work”, but it’s always good to verify. I speak from shoddy RegEx self-construction experience.

What you don’t match is just as important as what you do.

- Steve melting in a hot Aussie summer

Having said that, you allude to a great point — the ability of the RegEx to do things you don’t expect. I think that RegExperts like you are rare and should be worshipped. I am certainly one of your RegEx groupies. And always your RegEx student.

Robbin

Won’t just do what you’re after. This is where the .* construct can be too greedy.

As this will also match:
/mypage/otherfolder/index.htm

Which I suspect from your description is not what you’re after?

If you want only .htm files in the mypage directory, you need to construct the RegEx to stop from including any other directories.
How are directories identified? By slashes. So how do we not get a directory? By not having one or more slashes.

So the extract becomes:
/[^/]+\.htm$

/ - a directory (in our case to be prefaced by ^/mypage )

[^/] - Any *single* character, but NOT a slash.

+ - One or more of the previous. Unless you really expect to have a file called “.htm”, always expect at least one character. “a.htm”.

Rest is as you’ve described.

So the full RegEx becomes:

^/mypage/[^/]+\.htm$

The trick with this style of RegEx construction is to try and figure out what *else* you could match, inadvertently. This is one of the reasons why I try really hard not to use “.*”, preferring “.+”, as the zero case of “.*” can be unexpected.

HTH?

- Steve, GoobleDeGook Provider Extraordinaire