Clarification: I'm pretty much a
Perl/CPAN noob, don't assume I know
too much.
I have a pretty vanilla CPAN because I just rebuild my entire Lenny 5.0.2 VPS - so I pretty much have the default modules installed.
My eventual goal is to setup foswiki on my Apache 2.x based server.
So far I'm reading this guide and it says the first thing you should do is upgrade CPAN to the latest version. So I did (as su):
# perl -MCPAN -e '$ENV{FTP_PASSIVE} = 1; install CPAN'
Now, it's installing/updating a bunch of stuff, here's an excerpt:
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CPAN-Test-Dummy-Perl5-Make-Expect-1.00.tar.gz
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CPAN-Test-Dummy-Perl5-Make-UnsatPrereq-1.00.tar.gz
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CHECKSUMS
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/cpantestdummies/
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/cpantestdummies/CPAN-Test-Dummy-Perl5-Make-Features-1.05.tgz
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/cpantestdummies/CHECKSUMS
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CPAN-Test-Dummy-Perl5-Make-Zip-1.03.zip
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CHECKSUMS.2nd
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CPAN-Test-Dummy-Perl5-Make-1.05.tar.gz
CPAN-1.9402/t/CPAN/authors/id/A/AN/ANDK/CPAN-Test-Dummy-Perl5-Make-Failearly-1.02.tar.gz
CPAN-1.9402/t/CPAN/authors/id/A/AN/CHECKSUMS
CPAN-1.9402/t/CPAN/authors/id/A/CHECKSUMS
CPAN-1.9402/t/CPAN/authors/id/CHECKSUMS
CPAN-1.9402/t/CPAN/authors/01mailrc.txt
CPAN-1.9402/t/CPAN/CpanTestDummies-1.55.pm
CPAN-1.9402/t/CPAN/TestConfig.pm
CPAN-1.9402/t/51pod.t
CPAN-1.9402/t/02nox.t
CPAN-1.9402/t/50pod.t
CPAN-1.9402/t/10version.t
CPAN-1.9402/t/yaml_code.yml
CPAN-1.9402/t/04clean_load.t
CPAN-1.9402/README
CPAN: File::Temp loaded ok (v0.18)
CPAN.pm: Going to build A/AN/ANDK/CPAN-1.9402.tar.gz
Importing PAUSE public key into your GnuPG keychain... gpg: new configuration file `/root/.gnupg/gpg.conf' created
gpg: WARNING: options in `/root/.gnupg/gpg.conf' are not yet active during this run
done!
(You may wish to trust it locally with 'gpg --lsign-key 450F89EC')
Checking if your kit is complete...
Looks good
Writing Makefile for CPAN
Could not read '/root/.cpan/build/CPAN-1.9402-fmK7xK/META.yml'. Falling back to other methods to determine prerequisites
ANDK/CPAN-1.9402.tar.gz
make -- NOT OK
Warning (usually harmless): 'YAML' not installed, will not store persistent state
Running make test
Can't test without successful make
Running make install
Make had returned bad status, install seems impossible
kat:~#
I've searched Google and came across one page that said you should whenever possible install the package from aptitude/apt-get/yum, so I found a package named libyaml-perl, marked it for download, that went through fine.
Then I re-tried my initial command that installs the latest version of CPAN and ...
CPAN-1.9402/t/50pod.t
CPAN-1.9402/t/10version.t
CPAN-1.9402/t/yaml_code.yml
CPAN-1.9402/t/04clean_load.t
CPAN-1.9402/README
CPAN: File::Temp loaded ok (v0.18)
CPAN: YAML loaded ok (v0.66)
CPAN.pm: Going to build A/AN/ANDK/CPAN-1.9402.tar.gz
Importing PAUSE public key into your GnuPG keychain... done!
(You may wish to trust it locally with 'gpg --lsign-key 450F89EC')
Checking if your kit is complete...
Looks good
Writing Makefile for CPAN
ANDK/CPAN-1.9402.tar.gz
make -- NOT OK
Running make test
Can't test without successful make
Running make install
Make had returned bad status, install seems impossible
No clue what I should do now. Is there a way I can reset everything? Maybe I need to kill the file it tried to process so it can try to re-process it or something along those lines? If anyone else has general CPAN tips in addition to figuring out what this is, I'd be grateful.
Did I install the yaml package the right way?
Should I have done it from within CPAN?
What proper steps or modules should I get first?
Eventually I'll need to install these for foswiki:
CGI::Session - Needed for Foswiki's session feature which is really a must have
Error - Needed if you later want to develop plugins. It is also distributed with Foswiki but the author has experienced lots of trouble with the build script that builds plugins which sometimes cannot find this library. By adding it to the site Perl library you avoid this kind of trouble.
FreezeThaw - an indirectly needed module used by other modules.
GD - Used by the pluging that can produce graphics such as Foswiki:Plugins.ChartPlugin. It requires that lib gd is installed. If your choice of installation does not include you simply need to install the rpms gd and gd-devel. They are both on the CDs or DVD.
HTML::Tree - Needed by some popular plugins
Time-modules (Time::CTime, Time::DaysInMonth, Time::JulianDay, Time::ParseDate, Time::Timezone) also needed by some popular plugins.
Use debian's package management facilities to install: See instructions on the foswiki web site.
Stick with the platform-specific package management tools 99% of the time. Otherwise, configure CPAN to install in a separate directory (which you can add to $PERL5LIB).
What does o conf make in cpan shell say? Do you have make installed?
Generally, install build-essential (it's in ubuntu, so it should be also in Debian), and then do o conf init in cpan shell.
Consider using CPANPLUS (cpanp script) instead of CPAN.
Consider installing YAML before installing anything else.
Consider setting the configuration to follow prerequisites (that is, when some package requires some other module that is currently missing, it will go ahead and install the other module - recursively as necessary).
Related
I trying to get set up with Variant Effect Predictor (VEP) on the command line. I'm following the setup tutorial but I'm encountering some errors around dependencies. I'm also quite new to the command line so if anyone is able to break down the solution too then I'd be very grateful. Thanks!
Tutorial: https://www.ensembl.org/info/docs/tools/vep/script/vep_tutorial.html
VEP requirements: http://www.ensembl.org/info/docs/tools/vep/script/vep_download.html#requirements
I also have Perl v5.32.1.
What I've done:
I installed dependencies (listed in the requirements page) with the following commands:
- sudo -s cpanm DBI
- sudo -s cpanm Archive::Zip
- sudo -s cpanm DBD::mysql
For DBD:mysql, I got the follwoing message:
--> Working on DBD::mysql
Fetching http://www.cpan.org/authors/id/D/DV/DVEEDEN/DBD-mysql-4.050.tar.gz ... OK
Configuring DBD-mysql-4.050 ... N/A
! Configure failed for DBD-mysql-4.050. See /root/.cpanm/work/1626111140.5937/build.log for details.
Trying it out anyway, I ran perl INSTALL.pl (from the tutorial page) and got the message below. I would like VEP to run in online mode too if possible.
`WARNING: DBD::mysql module not found. VEP can only run in offline (--offline) mode without DBD::mysql installed
http://www.ensembl.org/info/docs/tools/vep/script/vep_download.html#requirements
Hello! This installer is configured to install v104 of the Ensembl API for use by the VEP.
It will not affect any existing installations of the Ensembl API that you may have.
It will also download and install cache files from Ensembl's FTP server.
Checking for installed versions of the Ensembl API...done
Setting up directories
Destination directory ./Bio already exists.
Do you want to overwrite it (if updating VEP this is probably OK) (y/n)? y
- fetching BioPerl
- unpacking ./Bio/tmp/release-1-6-924.zip
ERROR: Unable to unpack file ./Bio/tmp/release-1-6-924.zip without Archive::Extract or tar/unzip/gzip`
You show us this error:
Configure failed for DBD-mysql-4.050. See /root/.cpanm/work/1626111140.5937/build.log for details.
So looking in there will give you more clues about what the problems are. Without that, we can only guess.
But we can make educated guesses. The DBD::mysql distribution comes with a file called DBD::mysql::INSTALL which will talk you through some of the problems you'll find while installing this module.
It's important to note that DBD::mysql is a wrapper around MySQL's client libraries. They are written in C, so you'll need a C compiler installed in order to build DBD::mysql. You'll also need the client libraries and the development versions of the client libraries (for the C header files that you'll need to compile the module). On Ubuntu, those packages are called "libmysqlclient" and "libmysqlclient-dev". If you don't have a C compiler, then you'll want to install "gcc" too.
But this is all getting a bit complicated. There's another, simpler, approach. If you're using the system version of Perl (the version that was installed as part of the operating system and probably lives in /usr/bin/perl) then I'd recommend using the pre-build Ubuntu version of the package, which you can install by running:
$ sudo apt-get install libdbd-mysql-perl
Installing that version uses the OS's own package manager, and the package manager knows which other packages are needed in order for it to work - so it will install those as well.
People will probably complain that you're better off installing the modules from CPAN as it gives you more flexibility and allows you to use more up-to-date packages than the versions from your OS repos. And they're right. But, honestly, if you're a non-Perl programmer who just wants to get an application up and running, this is by far the simplest approach.
(But, as I said above, this is all guesswork as you haven't shared the most important errors with us.)
Because i have a long series of comments with #ikegami, I cleaning up the question, in a hope it will be more understandable. Unfortunately, english isn't my "main" language. :(
Let say, having an environment where:
no development tools are installed (no make, nor gcc or like)
perl is installed with its core packages, nothing more
no outgoing network access is allowed - e.g. the user couldn't use curl nor cpan to download/install perl dependencies
the user even doesn't have admin (root) rights
but want install and evaluate some perl based web-app, let call it as MyApp
The MyApp
doesn't uses any XS-based module. (at least, I hope - in the development me using plenv and cpanm, so never checked the installed dependencies in depth)
it is an pure PSGI app, the simple plackup app.psgi works OK
the app uses some data-files which should be included in the "deployment".
The main question is: how to prepare the MyApp, and the all used CPAN-modules, to be easily installed in such restricted environment?
The goal is:
i don't need save my efforts and my time
but i want save the user's time and want minimize the needed actions on his side, so the installation (deployment) should be simple-as-possible.
E.g. how to get an running web-app to the user's machine with minimum possible (his) steps.
- the simplest thing is could be something as:
- copy one file (zip, or tarbal)
- unpack it
- from the terminal execute some run.pl in the unpacked directory.
To get the above simple installation, my idea was the following:
1.) Create an tarball, and after the unpacking will contain 3 folders and 1 perl-script, let say:
myapp_repo/
myapp_repo/distlib #will contain all MyApp's perl modules also ALL used CPAN modules and their dependecies
myapp_repo/datafiles #will contain app-specific data files and such
myapp_repo/install.pl
myall_repo/lib #will contain modules directly used by the `install.pl`
2.) I will develop an install.pl script, and it will be used as the installer-tool, like
perl install.pl new /path/to/app_root
and it will (should):
create the all needed directories under the /path/to/app_root (especially the lib where the will install the perl modules)
will call "local" cpanm internally (from the myapp_repo/lib) to install the app's perl modules and their CPAN dependencies using only distribution files from the distlib.
will generate and install the needed runtime script and the app.psgi into the /path/to/app_root/bin
will install the needed data-files for the app.
3.) So, after this the user should be able to simply run:
/path/to/app_root/bin/plackup /path/to/app_root/bin/app.psgi
In short, the user should use:
the system-wide perl and the system-wide perl-core modules
and any other
runtime perl-scripts (like plackup)
and the required CPAN-modules
should be installed to an self-contained directory tree using only files (no net-access).
E.g. the install.pl should somewhat call internally the cpanm to achieve (as equivalent) for the following cpanm command
cpanm --mirror file://path/to/myapp_repo/distlib --mirror-only My::App
which, should install My::App and all dependencies without network access using only the files from the myapp_repo/distlib
Some questions:
Is possible to use cpanm (called as an locally installed module) without the make?
For creating the myapp_repo/distlib, me thinking about using Pinto. Is it the right tool for achieve the above?
forgot me something? or with other words:
Is the above an viable (read: working) way?
are are any other tools, which i could/should to use for simplifying the creation of such distribution tarball?
#ikegami suggesting some method:
- "install everything" in one fresh-directory on my machine
- transfer this self-contained directory to the target machine
It sound very good, because this directory could contain all the needed app-specific data-files too, unfortunately, I don't understand the details how his solution should be done.
The FatPacked solution looks interesting too - need learn about it.
Don't write your own make or installer. Just copy it make from a different machine (which is basically what apt/yum/etc do anyway, and which you'd have to do even if you wrote your own). You'd be able to use cpan in 5 minutes!
Also, that should allow you to install gcc if you need it (e.g. to install an XS module), although it doesn't sound like you do. If you do install gcc, I'd install my own perl to avoid having to deal with PERL5LIB.
Tools such as minicpan will allow you to install any module from CPAN without internet access. Of course, you can keep using the command you are already using it if mirrors the packages you need.
The above explains how to simply and quickly setup a machine so it can use cpan and thus install any module easily.
If you just want to install a specific module and its dependencies, you can completely avoid using cpan on the target machine. First, you need a fresh install of Perl (preferable of the same version as the one on the target system). Then, simply install the module to a fresh dir on your machine, and transfer that dir to the target machine. That's it; nothing else needs to be done. This even works for XS modules if the two machine are similar enough.
This is what ppm (ActiveState's Perl package manager) does.
Unfortunately, while this solution is almost as simple as the one above, it's not nearly as flexible, it doesn't run the test suite of the modules being installed, etc. It does have the advantage of not requiring the transfer of any binary (if you're not installing any XS modules).
I'm trying to install some perl modules as part of the set up for Circos. I'm installing the modules using cpan in terminal, and while the initial set up seems to go well, all the modules fail during the final step of the install, when the Makefile is being written.
Here's what the error looks like:
Checking if your kit is complete...
Looks good
Writing Makefile for Font::TTF
Can't exec "make": No such file or directory at /System/Library/Perl/5.12/CPAN/Distribution.pm line 2026.
MHOSKEN/Font-TTF-1.02.tar.gz
make -- NOT OK
'YAML' not installed, will not store persistent state
Running make test
Can't test without successful make
Running make install
Make had returned bad status, install seems impossible
Failed during this command:
MHOSKEN/Font-TTF-1.02.tar.gz : make NO
I think the only option might be to manually install the modules instead of using cpan, but I figured it might be worth a shot to put up a question here.
It seems that /System/Library/Perl/5.12/CPAN/Distribution.pm is trying to find your system's "make" command. Since you're using Mac OS/X is "make" actually installed or do you need to add some developer tools?
To further on G. Cito's answer/question:
This old answer might do the trick for you, if you're on Mac OS/X, as the exact same error is thrown in the respective circumstances:
https://stackoverflow.com/a/6767528/2352071
I was using ubuntu 12.04 until 12.10 was released. I used ubuntu for software development and after installing 12.10, i noticed that the perl version (5.14) shipped with 12.10 does not include the Switch.pm module needed while building WebKiT-GTK.
Looking around on the internet i found few suggestions indicating that i should install something call p5-switch from something called ports. I have looked around and was not able to get this done. I am not a perl guy and have no idea where i can get this package.
Can someone please help me as to
1. Where to download the package for ubuntu 12.10
2. In case it is not a .deb, How do i install it.
OR
1. At least be able to downgrade the perl installation to something lower than 5.14
Thanks and Regards
~Sameer
sudo apt-get install libswitch-perl
will install it for you.
"ports" is a *BSD packaging system of sorts, not what you should be looking for.
You can find what package has a particular perl module by going to packages.ubuntu.com, entering Module/Name.pm (in this case, Switch.pm) in the "Search the contents of packages" form and checking "packages that contain files whose names end with the keyword" and selecting the desired distribution, then making sure you ignore false hits like CGI/Switch.pm in the results. Debian has the identical search for its packages at packages.debian.org.
(Note that Switch.pm has serious limitations, was never really intended to be used in production, and should certainly not be used in new code.)
Do make sure you've checked properly that there isn't the Switch module available via apt. If it is available, that's the one you want.
No, then you've two options the longer, correct way and a shorter way that's not quite as clean.
1. Longer
Install cpanm and perlbrew with apt. The perlbrew tool lets you install a complete version of Perl from scratch in a separate directory. Set up a user for your webkit building, run perlbrew as that user, install your perl. Then, use cpanm to install required modules and you are done. A bit of googling will get you step-by-step examples of how to use these tools. If anything goes badly wrong, you can just delete all the files in that user's home directory and start again - all you waste is a little time.
The reason experienced Perl people prefer this is that it keeps the perl you want for webkit-gtk separate from your system perl that ubuntu's packages will expect to be unchanged from the one they ship.
2. Shorter
Install cpanm with apt. As root, run "cpanm Switch" and it will install the Switch.pm package and any dependencies. It will also upgrade any already installed packages it thinks it needs to. This last step is why this option isn't ideal. In the (rare) case when the update isn't compatible with something else on your system uninstalling is fiddly.
I'm trying to setup a Perl development environment on my Mac laptop and have been having a really hard time getting it working. I thought I had everything configured correctly but when I try to run a sample script it is reporting errors with the DBI module and can't access the DB.
Here is what is reported in the Apache error logs:
[Fri Apr 30 23:11:33 2010] [error] [client 127.0.0.1] Can't locate DBI.pm in #INC (#INC contains: /Library/Perl/Updates/5.10.0/darwin-thread-multi-2level /Library/Perl/Updates/5.10.0 /System/Library/Perl/5.10.0/darwin-thread-multi-2level /System/Library/Perl/5.10.0 /Library/Perl/5.10.0/darwin-thread-multi-2level /Library/Perl/5.10.0 /Network/Library/Perl/5.10.0/darwin-thread-multi-2level /Network/Library/Perl/5.10.0 /Network/Library/Perl /System/Library/Perl/Extras/5.10.0/darwin-thread-multi-2level /System/Library/Perl/Extras/5.10.0 .) at main.pm line 5.
I downloaded and installed both modules manually to work with MAMP using the following commands as specified in this forum post:
For DBI
1. cd /Library/Perl/DBI-1.611
2. sudo Perl Makefile.PL
3. sudo make
4. sudo make install
For DBD
1. cd /Library/Perl/DBD-mysql-4.014
2. sudo Perl Makefile.PL --mysql_config=/Applications/MAMP/Library/bin/mysql_config
3. sudo make
4. sudo make install
What I noticed while running the above commands is that the files seems to be getting installed in the '/opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/' directory which doesn't seem to be one of the search directories that Apache mentions in the error at the beginning of this post. Here is what I'm seeing during the install:
$ sudo make install
Files found in blib/arch: installing files in blib/lib into architecture dependent library tree
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBI.bundle
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbipport.h
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/DBIXS.h
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/dbixs_rev.h
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver.xst
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/Driver_xst.h
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/TASKS.pod
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/DBM.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/File.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBD/Gofer.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Changes.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/DBD.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/Profile.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/ProxyServer.pm
Installing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/DBI/PurePerl.pm
Installing /opt/local/share/man/man3/DBD::DBM.3pm
Installing /opt/local/share/man/man3/DBD::File.3pm
Installing /opt/local/share/man/man3/DBD::Gofer.3pm
Installing /opt/local/share/man/man3/DBI.3pm
Installing /opt/local/share/man/man3/DBI::DBD.3pm
Installing /opt/local/share/man/man3/DBI::Profile.3pm
Installing /opt/local/share/man/man3/DBI::ProxyServer.3pm
Installing /opt/local/share/man/man3/DBI::PurePerl.3pm
Installing /opt/local/share/man/man3/TASKS.3pm
Installing /opt/local/bin/dbiprof
Installing /opt/local/bin/dbiproxy
Writing /opt/local/lib/perl5/site_perl/5.8.9/darwin-2level/auto/DBI/.packlist
Appending installation info to /opt/local/lib/perl5/5.8.9/darwin-2level/perllocal.pod
My question is, what am I doing wrong and how can I either 1) Get Apache to look in the right directory where the DBD & DBI modules are installed or 2) Update the way I'm installing the module to install them into one of the search directories. I honestly don't know what option makes more sense and could use guidance on that as well.
As you can probably tell I'm pretty lost at the moment. Please help!!! Thanks in advance.
It looks like you've already installed another Perl via macports (/opt/local is where all macports installations go), and /opt/local/bin is earlier in your $PATH than the system Perl in /usr/bin. That's fine, if you are happy running Perl 5.8.9 rather than Perl 5.10.0 (hint: if you aren't sure of the differences, then the differences don't matter).
It's usually advised to not make extra installations to the system Perl. Apple may upgrade components through regular system updates, which could interfere with any modifications you have made, and if you make a mistake with an installation, it's difficult to remedy it without doing a full system reinstallation or having some serious understanding of the operating system guts. So, since you've already got another Perl installation ready, I would strongly encourage you to stick with that one.
However, you probably shouldn't be manually installing libraries if there is already a distribution available on macports. I used port search dbi and port search dbd to find them: the distributions are named p5-dbi and p5-dbd-mysql. You can install those like any other macports module: with sudo port install <distroname>. (You may need to install mod_perl itself, too.)
After that, you simply need to tell Apache/mod_perl to use that Perl installation rather than the system perl. I've never done that, so I can't advise on the best way to do it. However, quick searches on http://superuser.com suggest that the macports version of apache will run by default (via the same $PATH ordering), so I'd just Try It And See :).
Great answer, Ether. Having done this far too many times to count, I can give you a few pieces of advice:
Note: I am apparently limited to a single link in the post, so I had to remove all of my annotations. Thankfully, there is Delicious where I've stored them all with a stackoverflowmacports tag. Any place below where I removed a link to fit under Stack Overflow's ridiculous anti-spam measure, I've marked it with (*).
If having a reliably-working development environment at all times is important to you, rely on as LITTLE Mac OS X bundled software as possible. I love Apple but they have absolutely no qualms about breaking custom setups of their software as often as possible.
If #1 sounds like what you need to do, Macports is an EXCELLENT choice. I used to use Fink but they got left in the dust ages ago in terms of ease of use and spectrum of available software. The easiest route to installing macports is via the binary package install method (*)
As Ether mentions, when you have everything set up correctly, the Macports-provided MySQL, PHP and Apache all work together well without the system-installed analogs interfering. Most of that has to do with your PATH setting but all of those details are handled by the package installers post-flight script (*)
Once you're on the Macports train, it should become the very first place you look for any software. port search and port info are constant companions. They've got 6863 ports (*) currently which covers MOST of your bases.
When you do need to go outside of the Macports realm to find something, install it in /usr/local. That part of the file system hierarchy is yours to play with. Don't be lulled into a false sense of security and think that because Macports doesn't have what you're installing, it's okay to put it in /opt/local because invariably that software will install some dependency that will ALSO be a dependency for some piece of Macports software down the line and Macports will not allow a port to be installed if any one of its files would overwrite an existing file not managed by Macports (unless you force it which is always bad manners)
If you do any work with Perl and you use Macports' version, you will absolutely find yourself in a situation Macports doesn't have the one CPAN module you're looking for. (And, really, given that there are two and a half billion CPAN modules, who can blame them?). This will happen often enough that you will most likely tire of the manual installation method (*) (perl Makefile.PL; make; make test; sudo make install; cha; cha; cha) and long for the ease of use you've grown accustomed to with Macports.
If so, you can absolutely use the cpan (*) utility, CPANPLUS (*) or cpanminus (*) for all of your installing needs. Just make sure to make the necessary adjustments in the configuration of your tool of choice to instruct it to install your modules into /usr/local/lib/perl5, ignoring /opt/local/bin/perl's insistence that modules go into /opt/local/lib/perl5. You can set the PERL5LIB environment variable in your shell's init scripts to additionally look in /usr/local/lib/perl5 for modules. Just grab the #INC output from perl -V and tack it on the end...
And finally... Leveraging the system's daily init scripts or third-party software like Anacron (*) or MacPorts Notifier (*) (both available through MacPorts), make sure to update your software frequently. You don't have Mother Apple protecting you with Software Updates for the Macports installed software which have just as many bugs and security exploits as the very same software Apple bundles.
By updating frequently, you'll stay ahead of the baddies and by automating it, the upgrades will actually happen and you won't end up as I have in the past with a full weekend blown because you had a mountain of outdated ports to upgrade. Note: Macports stages its updates and if it fails at any point, your current version continues to work. Apple could learn a thing or two from them, I tell ya...
So, that's all I can think of a the moment. Hopefully the lessons above will get you going quickly and save all of the time, effort and stress I've experienced in past years in learning it. I would argue it's still far better than the alternative: Hating Apple because they break all of your nice things... :-)
I had a similar problem with Apache using the wrong Perl. I fixed it by appending the following lines to my httpd.conf file:
SetEnv PATH [colon-separated list of directories]
SetEnv PERL5LIB [colon-sep'd list of directories]
In my case, it looked like this:
SetEnv PATH /opt/local/bin:/opt/local/sbin:/usr/local/bin:/usr/local/mysql/bin:$PATH
SetEnv PERL5LIB /opt/local/lib:/usr/local/lib