If MASTER_SITES is set to MASTER_SITE_PERL_CPAN, then preferred value of MASTER_SITE_SUBDIR is top-level hierarchy name. For example, the recommend value for p5-Module-Name is Module. The top-level hierarchy can be examined at cpan.org. This keeps the port working when the author of the module changes.
The exception to this rule is when the relevant directory does not exist or the distfile does not exist in the directory. In such case, using author's id as MASTER_SITE_SUBDIR is allowed.
All of the tunable knobs below accept both YES and a version string, like 5.8.0+. Using YES means that the port can be used with all of the supported Perl versions. If a port only works with specific versions of Perl, it can be indicated with a version string, specifying a minimal version (e.g. 5.7.3+), a maximal version (e.g. 5.8.0-) or an exact version (e.g. 5.8.3).
表格 6-4. Variables for ports that use perl
| Variable | Means |
|---|---|
| USE_PERL5 | Says that the port uses perl 5 to build and run. |
| USE_PERL5_BUILD | Says that the port uses perl 5 to build. |
| USE_PERL5_RUN | Says that the port uses perl 5 to run. |
| PERL | The full path of perl 5, either in the system or installed from a port, but without the version number. Use this if you need to replace ``#!''lines in scripts. |
| PERL_CONFIGURE | Configure using Perl's MakeMaker. It implies USE_PERL5. |
| PERL_MODBUILD | Configure, build and install using Module::Build. It implies PERL_CONFIGURE. |
| Read only variables | |
|---|---|
| PERL_VERSION | The full version of perl installed (e.g., 5.00503). |
| PERL_VER | The short version of perl installed (e.g., 5.005). |
| PERL_LEVEL | The installed perl version as an integer of the form MNNNPP (e.g., 500503). |
| PERL_ARCH | Where perl stores architecture dependent libraries. Defaults to ${ARCH}-freebsd. |
| PERL_PORT | Name of the perl port that is installed (e.g., perl5). |
| SITE_PERL | Directory name where site specific perl packages go. This value is added to PLIST_SUB. |
注: Perl 模組的 port，由於沒有正式的網站，所以 pkg-descr 內的 WWW 應該指向至 cpan.org。 比較好的 URL 格式是 http://search.cpan.org/dist/Module-Name/ (包括結尾的 / 斜線符號)。