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knb
Asked: 2012-05-16 23:58:27 +0800 CST

How to conserve/copy perl 5.12 installation before upgrading to ubuntu 12.04?

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Ubuntu 12.04 is out, and I want to upgrade. However, I need to conserve my existing perl 5.12 installation before upgrading. On 12.04, there is perl 5.14 and I would need to reinstall lots of perl modules. I better copy my existing perl installation before ugrading, because the installer will remove the old perl stuff and I cannot determine what I need when the 5.12 modules are gone.

Any ideas how to do this? I have a mix of modules installed from repos, from cpanm, from cpan, and from source. I need

  • a strategy to determine a comprehensive list of my perl modules, their respective origins
  • a sequence in which order to proceed.
  • advice on what to do in case a certain module is not yet available in 5.14.
  • advice on which environment variables and paths to change.
installation perl 12.04

1 Answers

  1. Best Answer

    I would recommend breaking this question up into several parts in order to simplify the responses.

    My suggestions below are only a rough outline of my previous migration experiences. I would recommend that you follow up with additional reading.

    1. Develop a strategy to determine a comprehensive list of my Perl modules, and their respective origins

      There are several methods of determining which Perl modules are installed on your system.

      The following command: 

      find -L `perl -e '{print join $/, grep {/[^.]/} @INC}'` -name '*pm' 2>/dev/null

      will list all perl modules including those installed by the default package.

      There are two other commands that can simplify the list to include manually installed modules:

      The command perldoc perllocal will list some details about the modules version and their installed location.

      Another command is sudo instmodsh. which will provide a simple list of installed modules.

      There are other questions posted here that may help determine whether your module is part of the core distribution or not.

    2. Build a migration plan to determine the order to proceed with the migration.

      I would recommend using Perl's autobundle option to create a snapshot of your installed modules using the command: perl -MCPAN -e 'autobundle'

      The final output will be something like this:

      wrote bundle file /home/somerandomuser/.cpan/Bundle/Snapshot_2012_11_13_00.pm

      Be sure to make a note of that file as you will need it to restore the snapshot later when issuing the next command after your system upgrade:

      perl -MCPAN -e 'install Bundle::Snapshot_2012_11_13_00'

    3. Advice on what to do in case a certain module is not yet available in 5.14.
      Read about the different modules on CPAN and their availability in new Perl releases.

    4. Finally, and most importantly, I would highly recommend installing Perlbrew and TEST. TEST. TEST. My instructions are not meant to be taken as a step-by-step failproof installation guideline but a rough outline of the process

    I hope that this points you in the right direction.

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