[rt-users] General hints and tips when installing perl modules and using CPAN

[Bob Apthorpe]

Hi,

Following Bruce's lead, I'd like to add a few notes on perl and CPAN:

1) Before installing anything (else), manually upgrade CPAN.pm to the most 
recent version. Download the tarball from cpan.org, unpack, and install as 
any other perl module (perl Makefile.PL; make; make test; make install).

Do not use CPAN to install CPAN.pm. CPAN.pm versions 1.48 and earlier do not 
ask permission before upgrading core perl when installing modules that are 
now maintained as part of core perl (Data::Dumper, File::Spec, etc.) For this 
reason, it's important to install a recent version of CPAN.pm and configure 
it to ask permission before installing prerequisites, e.g.:

# perl -MCPAN -e shell
cpan> o conf prerequisites_policy ask
cpan> o conf commit
cpan> quit

You can also do this when you initialize CPAN for the first time.

2) Set CPAN to uninstall old modules when conflicts occur with

# perl -MCPAN -e shell
cpan> o conf make_install_arg   UNINST=1
cpan> o conf commit
cpan> quit

You can also do this when you initialize CPAN for the first time.

3) CPAN stores downloaded modules under 
$HOME/.cpan/sources/authors/id/Z/ZZ/ZZZ... so if you have trouble 
installing modules automatically, you can find fresh sources here.

4) Solaris 8 users: I feel your pain. You have two choices with regards to 
CPAN:

a) Scrape out the heinously borked version of perl 5.005_03 that Sun supplies 
you and install a new (5.6.1 or later) clean copy from source so that all the 
files go in the right places (Hint: /usr/perl5/bin is where vital utilities 
like h2xs, h2ph, perldoc, and find2perl live. Paraphrasing Dave Barry, "Who 
installed this code? Vandals?") Also, make sure the C compiler you build perl 
with is available after installation (see below.)

b) Presuming you don't have Sun's C compiler (and who does?), save a backup 
copy of 
/usr/perl5/5.00503/sun4-solaris/Config.pm
and in the original, replace references to cc with gcc, being careful to 
change the values of 'optimize' and 'cccdlflags' to reflect the appropriate 
gcc options ('-KPIC' -> '-fPIC', '-xO3 -xdepend' -> '-O3'). 

/usr/perl5/5.00503/sun4-solaris/Config.pm 'remembers' how perl was built and 
is used by CPAN (via MakeMaker) to build makefiles to install modules. You 
can change some of the options in CPAN to convince it to use gcc instead of 
Sun's hypothetical compiler but it's often much cleaner to erase cc from 
Config.pm or just install a recent version of perl from scratch. I don't have 
many comments about the Solaris packages of perl on sunfreeware.com or 
sunsite/ibiblio; I've had good results with packages from both archives but I 
simply don't trust *anyone's* package of perl, especially when Sun is 
involved.

5) Perl 5.6.0 is a troubled version. If feasible, upgrade to 5.6.1 or later.

6) Rarely do I have to force-install a package. Tests generally fail for a 
reason and really, you should investigate the failed tests before forcing an 
installation, just to ensure the test results can be safely neglected. Some 
tests fail if they're run as root. Common problems are missing library paths 
(requiring LD_LIBRARY_PATH and LD_RUN_PATH to be specified) and missing or 
outdated .ph files (perl-massaged include files for system libraries.) Update 
the .ph files with:

cd /usr/include; h2ph -r -l .

You should only need to do this once, or whenever you update the contents of 
/usr/include. See the h2ph manpage for details (Solaris users should use 
'/usr/perl5/bin/perldoc /usr/perl5/bin/h2ph' instead...)

-- Bob

On Wednesday 27 February 2002 15:25, you wrote:
> ( This message is aimed for the archives and anyone trying to solve a
>   particular problem.  It contains broad advice )
>
> If you are attempting to install any of the perl modules listed in the
> subject line, please remember to have installed the include files and
> libraries that may be an optional part of the software package.
>
> Some, well-known, OS distributions offer you a choices of binary-only,
> binary-with-include, binary-with-lib (etc) installations of a given
> software package.  For RT, these software packages are generally Apache
> and MySQL
>
> Please install the software package *with* the include files and *with*
> the libraries.
>
> You may not to be able to install certain perl modules (CPAN) without the
> software package's include and library files.  Installing these may solve
> your problems.
>
> Linux 'binary' packages are the main culprits in this regards.
>
> Regards,