.htaccess DirectoryIndex /subfolder/index.php seems to manage links in a funny way

Question

• I have the default myIndex.php in a subfolder of public_html.

• I added a file .htaccess in public_html.

• I added DirectoryIndex /subfolder/myIndex.php in it.

myIndex.php contains links and includes. Includes seems to work but links dont: no images and no css but menu.php is included. Links in menu.php dont work either.

If I

• change .htaccess to DirectoryIndex index.php,

• create a file index.php in public_html,

• and put a link to "./subfolder/myIndex.php" in it

  everything works fine.

I dont understand what happens here.

Answer 1

DirectoryIndex determines what to do, when a client requests a directory. If you have

DirectoryIndex /subfolder/myIndex.php

then exactly this script will be executed every time the client requests a directory, no matter where this directory is, e.g. /anotherfolder/ or /static/. But when you have

DirectoryIndex index.php

instead, Apache looks for an index.php in the requested directory, e.g. /anotherfolder/index.php or /static/index.php.