[tex-live] Where is the master control switch?

[Thomas Esser]

> 1. Does a texmf.cnf need to be available at compile time when the
> various tex programs are built?

Yes. paths.h gets the default for TEXMFCNF from it (plus a few other
defaults). A texmf.in in contained in the source tree and texmf.cnf
and paths.h are automatically generated out of it. You don't need an
installed texmf.cnf file.

> In general, does the texmf tree as a
> whole need to be installed for best results before compiling tex programs?

No.

> 2. There are so many choices.  I'm wondering about best practices for 
> handling the numerous variables named in all-caps, found in texmf.cnf 
> and elsewhere: TEXMFMAIN, TEXMFLOCAL, TEXMFDBS, VARTEXFONTS, etc.

That's easy: just make sure that the path in paths.h has a good
compile-time default for TEXMFCNF. Next is to make sure that the texmf.cnf
file *at runtime* has good values for these variables.

> - command line parameters to "configure"?
No.

> - environment variables present when configure is run?
No.

> - entries in texmf.cnf (presuming that TEXMFCNF has been set already)
Yes.

> - or, environment variables present at runtime?
Better avoid that.

> 3. I have already observed that setting TEXMFMAIN as an environment
> variable at runtime is inadequate.  How many such variables would need

It works to overwrite what a possible texmf.cnf file would define. Maybe,
your problem was something else...

Have you considered to set KPATHSEA_DEBUG=-1 (envvar, produces a lot
of debugging output)? Have you checked if some variables are derived by
some SELFAUTO* variables? These are always set relarive to the location
of the binary and cannot be overwritten in the environment.

Thomas