[tex-live] reporting tex-related envvars at install time

[Karl Berry]

A while ago, Werner suggested:

    Date: Sun, 21 Sep 2008 07:20:18 +0200 (CEST)
    From: Werner LEMBERG

    As a corollary of this thread: Maybe the installer should do something
    like this:

      set | grep -i tex | less

    to show the user what environment variables related to tex (or not)
    are set, together with a message that the user have to check them.

I just added this check to install-tl, although I rather worry that
there will be too many false positives.  If anyone notices particular
variables which are not a problem, please report so they can be
excluded.  I already exclude $PWD, $OLDPWD, $_, and various others.

Thanks,
Karl

Here's what the message looks like:

 ----------------------------------------------------------------------
 The following environment variables contain the string "tex"
 (case-independent).  If you're doing anything but adding personal
 directories to the system paths, they may well cause trouble with
 some parts of running TeX.  If you encounter problems, try unsetting
 them.  (And please ignore any spurious matches that are unrelated to TeX.)

    TEXMFCACHE=/home/karl/.texlive2009/texmf-var
 ----------------------------------------------------------------------

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