At any given time, the package perl should represent the current stable upstream version of Perl revision 5 (see Appendix A, Perl 6).

Only one package may contain the /usr/bin/perl binary and that package must either be perl or a dependency of that package (see Section 2.2, “Base Package”).

Where possible, Perl should be compiled to provide binary compatibility to at least the last released package version to allow a grace period over which binary module packages may be re-built against the new package (see Section 4.4.2, “Binary and Other Architecture Dependent Modules”).

The perl-base package must provide perlapi-abiname for all released package versions it is compatible with. The choice of abiname is arbitrary, but if it differs from $Config{version}^[1], it must be specified in $Config{debian_abi}.

In order to provide a minimal installation of Perl for use by applications without requiring the whole of Perl to be installed, the perl-base package contains the binary and a basic set of modules.

As Perl has been part of the essential set for some time and is used without dependencies by such things as package maintainer scripts, perl-base must be priority required and marked as essential.

Note that the perl-base package is intended only to provide for exceptional circumstances and the contents may change. In general, only packages which form part of the base system should use only the facilities of perl-base rather than declaring a dependency on perl.

Perl searches several different locations for modules, referred to in this document as core in which modules distributed with Perl are installed, vendor for packaged modules and site for modules installed by the local administrator.

The module search path (@INC) in the current Debian packages has been ordered to include these locations in the following order^[2]

In each of the directory pairs above, the lib component is for binary (XS) modules, and share for architecture-independent (pure-perl) modules.

The POD files and manual pages which do not refer to programs may be split out into a separate perl-doc package.

Manual pages distributed with packages built from the perl source package must be installed into the standard directories:

The extensions used for manual pages distributed with module packages are different. See Section 4.1, “Vendor Directories”.

The Perl packages must provide a mechanism for the local administrator to install modules under /usr/local but must not create or remove those directories.

Modules should be installed to the directories described above in Section 2.3, “Module Path” as site (current), programs to /usr/local/bin and manual pages under /usr/local/man.

The following commands should be sufficient in the majority of cases for the local administrator to install modules and must create directories as required:

perl Makefile.PL
make install

The installation directory for Debian modules must be different from that for core and site modules.

The current Perl packaging uses the vendor directories for this purpose, which are at present as described in Section 2.3, “Module Path” as vendor.

The Perl distribution includes many modules available separately from CPAN which may have a newer version. The intent of the @INC ordering (described in Section 2.3, “Module Path”) is to allow such modules to be packaged to vendor which take precedence over the version in core. A packaged module which shadows a core module in this way must be a newer version.

Module packages must install manual pages into the standard directories (see Section 2.4, “Documentation”) using the extensions .1p and .3pm to ensure that no conflict arises where a packaged module duplicates a core module.

.packlist files should not be installed.

Perl module packages should be named for the primary module provided. The naming convention is to lowercase the Perl module name, prepend, lib, change all occurrences of :: to -, and append -perl. For example:

Packages which include multiple modules may additionally include provides for the additional modules using the same convention.

A module should use the following lines in the debian/rules build target: ^[7]

perl Makefile.PL INSTALLDIRS=vendor
$(MAKE) OPTIMIZE="-O2 -g -Wall"

and this one to install the results into the temporary tree:

$(MAKE) install DESTDIR=$(CURDIR)/debian/<tmp>

^[8]

All packaged perl programs should start with #!/usr/bin/perl and may append such flags as are required.

Programs which require core modules from the perl package must specify a dependency on that package.

Programs which contain explicit require version or use version statements must specify a dependency on perl or perl-base with the minimum required version, or more simply the current version.

As with modules, packages using debhelper may use dh_perl(1) to automatically generate dependencies (see Section 4.4.3, “Automating Perl Dependencies”).

Programs which embed a perl interpreter must declare a Build-Depends on libperl-dev.

The default linker options produced by

perl -MExtUtils::Embed -e ldopts

will link against the dynamic libperl. If programs wish to link to the static library, then -lperl should be changed to /usr/lib/libperl.a in those options.

Dependencies for programs linking against the shared Perl library will be automatically created by dpkg-shlibdeps. Note however that the shared perl library package only suggests perl-base and packages requiring any core modules from the perl package must depend upon it explicitly.

Starting from perl 5.12.3-2, a dpkg trigger named perl-major-upgrade will be triggered by the postinst of the perl package during major upgrades. Some examples of things which constitute a major upgrade are an upgrade which would change the value of versioned directories in @INC, or one which changes abiname. Any package may declare an interest in the trigger, especially packages including long-running daemons which would stop working until restart.

It is suggested that such packages include an appropriate section in their postinst to handle the trigger by restarting relevant daemons or notifying users of further action.