I recently needed to run 32-bit Perl 5.8 on a 64-bit Centos 6 system. Initial research suggested that perlbrew would be the easiest way of achieving this, but I wasn’t able to find a walkthrough.

Here’s what worked for me…

1. Install perlbrew

You’ll need to install perlbrew from the CPAN, and it has a load of dependencies. The wonderful App::cpanminus makes this experience as painless as possible, so I installed it before moving onto perlbrew itself.

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$ sudo yum install perl-CPAN
$ sudo cpan App::cpanminus
$ sudo cpanm install App::perlbrew

1. Initialise perlbrew

Next, get perlbrew ready for use. Pay attention to the output of the init step – it will direct you to make a change to your shell configuration.

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$ perlbrew init
$ perlbrew install-patchperl

2. Install 32-bit Libraries

Installing these two packages was enough to build a 32-bit perl core. If you’re building additional XS modules against the 32-bit perl, they may require other 32-bit libraries to be installed.

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$ sudo yum install glibc-devel.i686 libgcc.i686

3. Build A Perl

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$ perlbrew install 5.8.9 -Accflags="-m32 -march=i686" -Aldflags="-m32 -march=i686" -Alddlflags="-shared -m32 -march=i686"
Fetching perl-5.8.9 as /home/zts/perl5/perlbrew/dists/perl-5.8.9.tar.bz2
Installing /home/zts/perl5/perlbrew/build/perl-5.8.9 into ~/perl5/perlbrew/perls/perl-5.8.9

This could take a while. You can run the following command on another shell to track the status:

  tail -f ~/perl5/perlbrew/build.perl-5.8.9.log

perl-5.8.9 is successfully installed.

That’s all there is to it, though the result isn’t quite perfect. While the above invocation builds a 32-bit perl, it doesn’t override the system’s archname – so the resulting @INC looks like this:

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@INC:
    /home/zts/perl5/perlbrew/perls/perl-5.8.9/lib/5.8.9/x86_64-linux
    /home/zts/perl5/perlbrew/perls/perl-5.8.9/lib/5.8.9
    /home/zts/perl5/perlbrew/perls/perl-5.8.9/lib/site_perl/5.8.9/x86_64-linux
    /home/zts/perl5/perlbrew/perls/perl-5.8.9/lib/site_perl/5.8.9
    .

For my purposes, this is simply an aesthetic issue – the x86_64-linux directories contain 32-bit shared objects – and I chose not to spend any more time perfecting it. If you happen to know which option(s) I’m missing, please leave a comment below.