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Notes on Perl

General Notes

For our scripts, we rely quite a bit on Perl, and increasingly on some core Perl modules. These Perl modules are part of the Perl source, so if you build Perl on your own, you should be set.

However, if you install Perl as binary packages, the outcome might differ, and you may have to check that you do get the core modules installed properly. We do not claim to know them all, but experience has told us the following:

  • on Linux distributions based on Debian, the package perl will install the core Perl modules as well, so you will be fine.
  • on Linux distributions based on RPMs, you will need to install perl-core rather than just perl.

You MUST have at least Perl version 5.10.0 installed. This minimum requirement is due to our use of regexp backslash sequence \R among other features that didn't exist in core Perl before that version.

Perl on Windows

There are a number of build targets that can be viewed as "Windows". Indeed, there are VC-* configs targeting VisualStudio C, as well as MinGW and Cygwin. The key recommendation is to use a Perl installation that matches the build environment. For example, if you will build on Cygwin be sure to use the Cygwin package manager to install Perl. For MSYS builds use the MSYS provided Perl. For VC-* builds we recommend Strawberry Perl, from http://strawberryperl.com. An alternative is ActiveState Perl, from http://www.activestate.com/ActivePerl for which you may need to explicitly select the Perl module Win32/Console.pm available via https://platform.activestate.com/ActiveState.

Perl on VMS

You will need to install Perl separately. One way to do so is to download the source from http://perl.org/, unpacking it, reading README-VMS.md and follow the instructions. Another way is to download a .PCSI file from http://www.vmsperl.com/ and install it using the POLYCENTER install tool.

Required Perl modules

We do our best to limit ourselves to core Perl modules to keep the requirements down. There are just a few exceptions.

For Building

  • Text::Template

    This module is not part of the core Perl modules. As a matter of fact, the core Perl modules do not include any templating module to date. This module is absolutely needed, configuration depends on it.

For Testing

  • Test::More

    We require the minimum version to be 0.96, which appeared in Perl 5.13.4, because that version was the first to have all the features we're using. This module is required for testing only! If you don't plan on running the tests, you don't need to bother with this one.

To avoid unnecessary initial hurdles, we have bundled a copy of the following modules in our source. They will work as fallbacks if these modules aren't already installed on the system.

Text::Template

Notes on installing a Perl module

There are a number of ways to install a perl module. In all descriptions below, Text::Template will serve as an example.

  1. for Linux users, the easiest is to install with the use of your favorite package manager. Usually, all you need to do is search for the module name and to install the package that comes up.

    On Debian based Linux distributions, it would go like this:

    $ apt-cache search Text::Template
...
libtext-template-perl - perl module to process text templates
$ sudo apt-get install libtext-template-perl

    Perl modules in Debian based distributions use package names like the name of the module in question, with "lib" prepended and "-perl" appended.

  2. Install using CPAN. This is very easy, but usually requires root access:

    $ cpan -i Text::Template

    Note that this runs all the tests that the module to be installed comes with. This is usually a smooth operation, but there are platforms where a failure is indicated even though the actual tests were successful. Should that happen, you can force an installation regardless (that should be safe since you've already seen the tests succeed!):

    $ cpan -f -i Text::Template

    Note: on VMS, you must quote any argument that contains upper case characters, so the lines above would be:

    $ cpan -i "Text::Template"

    and:

    $ cpan -f -i "Text::Template"