How do I make my new perl 5.8 recognise the any previously installed modules seen under 5.6?
There's no reason why it should. Each perl installation has its own directory tree. Unlike some software, the tree is not overwritten when you upgrade.
Is there a reason why the new perl installs by default into a different directory?
This has the advantage of allowing you to run both versions in parallel on the same box without them interfering with each other. Also, note that binary XS modules may be incompatible, and may require different builds.

The install mechanism (make install) picks up the path information from the config with which perl was built, together with other information such as which C compiler to use, compiler and link options, etc.

As others have said, perl -V will tell you this, and a whole lot more.

How do I make my new perl recognise newly installed modules?
It should be doing so, if you are installing them under the new perl.

As an alternative, you might want to share some modules between both versions. You can do this by installing to your own home grown install directory. 

perl Makefile.PL LIB=/home/me/lib
make
make test
make install

[download]
You need to get this path added to PERL5LIB, which will add it to @LIB without you needing to worry. Add the following to your .bashrc: 
export PERL5LIB=/home/me/lib

[download]
Hope this helps

--
I'm Not Just Another Perl Hacker

In reply to Re: where do perl modules install? by rinceWind
in thread where do perl modules install? by Clunk

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