Useful or not, from you.
install-freedos wrong libexecdir on ubuntu

dosemu2 gets the libexecdir via dh_auto_configure. But install-freedos only uses dh_auto_install and doesn't get the libexecdir. I tried the $(libexecdir) and $(prefix) variables, but they do not exist in dh_auto_install.

@skitt could you please tell me how to access the ubuntu directories in dh_auto_install (eg for the packages w/o configure)?

That's a useful answer
Without any help

OK, I see what you mean: that I need to set compat to 12 in dosemu2 and touch nothing in install-freedos, and then dh_auto_configure won't matter when talking about libexec (but my question was about all such paths, eg I don't like the hard-coded prefix too - I'd better get it from where dh_auto_configure gets it).

Debian isn’t Fedora (and yes, some aspects of RPM macros are nice, I’m not saying one is better than the other). It’s fine to have hard-coded paths in debian/rules etc., because the reference isn’t any build tool, it’s Policy. So we declare we comply with a certain version of Policy, using the Standards-Version field in debian/control; and that (Policy) is the source of truth.

Again, debhelper is only a helper, not a source of truth.