cpan

CPAN, the Comprehensive Perl Archive Network, is a distributed repository of Perl software. It provides a central resource for Perl modules, distributions, and documentation and is maintained by a global network of volunteers. CPAN mirrors around the world make the contents available by download and via indexing services and search tools.

Origins and infrastructure: CPAN emerged in the mid-1990s as a collaborative effort to centralize Perl modules. Authors upload distributions to PAUSE (Perl Authors Upload Server); the uploads are processed, indexed, and mirrored. CPAN tooling such as CPAN.pm, the CPAN shell, and more recent cpanm automate the installation and management of modules. MetaCPAN provides a modern web-based search interface and API for metadata.

Contents and packaging: Each distribution typically contains one or more Perl modules, tests, and metadata such as prerequisites and licenses. Build systems such as Makefile.PL (ExtUtils::MakeMaker) or Build.PL (Module::Build) are used to compile or install software. CPAN metadata describes dependencies, version requirements, and licensing to help automated installers resolve requirements.

Usage and impact: Developers rely on CPAN to share code, discover reusable components, and manage dependencies. The CPAN ecosystem includes the CPAN Testers project, which collects test results from various environments, contributing to quality control. Once installed, modules can be updated via CPAN clients such as cpan or cpanm.

Governance and scope: CPAN is a collaborative project coordinated by volunteers. It operates as a network of mirrors and indexing services rather than a single organization and remains a primary resource in the Perl community for distributing software and documentation.