[tex-live] Perl for Windows

[Fabrice Popineau]

* Reinhard Kotucha <reinhard.kotucha at web.de> writes:

    > Hi, when I install the complete TeXLive system on Windows XP, the
    > installer does not check whether there is another version of Perl
    > already installed on the system.

Any system relying on 3rd parties programs like Ghostscript, Perl or
whatever that are non standard (and for which sources are publicly
available) can't rely on existing versions of these tools (versions
installed on the client machine). The problem is that there is no way to
check that the features you expect from these tools are provided (or in
the best case, it is a nightmare to maintain). There are too many
version of Perl, of GS or even of the zlib library. Moreover many of
these tools do not publish themselves by following the MS guidelines so
you may have to check by yourself for conflicts. It happened that
Rational Rose (http://www.ibm.com/software/rational) came with and
mf.exe executable ... that was found on the PATH. Other products may use
gswin32c.exe or perl.exe or whatever.

[1] _The only reliable way is to provide the version you need and to hide it
from the rest of the system._

    > TL prepends the path/to/binaries to PATH and sets the environment
    > variable PERL5LIB accordingly.

I may have done that in the past and I agree that it was wrong. However
in this case you are using an old version of TL.

    > The Perl version which had been installed before TeXLive has set
    > the value of PERL5LIB somewhere else rather than in the
    > environment variables dialog box, maybe in the registry.  Don't
    > know how Windos works.

There is nothing secret in the registry. It behaves much like the
environment, except that it is system and lan wide for any user/machine.
It is a distributed database.

At one point, the GS guy changed their mind in the way they were looking
for the gs library. In the old days, they looked for GS_LIB in the
environment, and if it were not found, they looked into the
registry. And when they switched to the 8.x series (AFAIR), they stopped
looking into the environment, which means they prevented people to
locally override settings.

    > It should be sufficient to add texmf*/scripts to PERL5LIB if Perl
    > is installed already.

And cross your fingers and pray for this stuff to work. At some point,
texlive supported the texdoctk program that needed perl + tk + the right
extensions ... Are you sure that because you find perl.exe on the client
machine, you will find also everything you need ? See my [1] point.

Regards,

-- 
Fabrice