or how not to give a link in exchange of a link.
In the HTTP header, we can set the X-Robots-Tag :
header("X-Robots-Tag: noindex", true);
will prevent search engines from showing the file.
However, you could prevent search engines from following the links on those pages, by doing the following:
header("X-Robots-Tag: nofollow", true);
The links on the page will appear as followed when they are not followed.