How to set Apache conditional header based on URL?

Question

I want to set different HTTP header depending on the URL. In my particular case I want a specific URL (e.g. regex ^/abc$) to have a different header than all th

Answer 1

This is a one-line alternative taken from documentation:

Header always set CustomHeader my-value "expr=%{REQUEST_URI} =~ m#^/special_path.php$#"