PortGroups are simply include files for portfiles. They can define as much or as little as a portgroup author feels is necessary to provide a set of definitions or behaviors common to a group of portfiles, in order that those portfiles can be expressed as simply as possible with minimum redundancy.

See the following folder for PortGroup definitions:

${prefix}/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports/_resources/port1.0/group/

or if you prefer directly in GitHub .

A sample listing follows:

%% ls -1 /opt/local/var/macports/sources/rsync.macports.org/macports/release/tarballs/ports/_resources/port1.0/group/

active_variants-1.1.tcl
apache2-1.0.tcl
app-1.0.tcl
archcheck-1.0.tcl
bitbucket-1.0.tcl
cmake-1.0.tcl
cmake-1.1.tcl
compiler_blacklist_versions-1.0.tcl
compilers-1.0.tcl
conflicts_build-1.0.tcl
crossbinutils-1.0.tcl
crossgcc-1.0.tcl
cxx11-1.0.tcl
cxx11-1.1.tcl
debug-1.0.tcl
elisp-1.0.tcl
github-1.0.tcl
...

The requirements of a minimum portfile using a portgroup varies by portgroup. The sections below devoted to each portgroup (or, for portgroups not documented there yet, the comments in the header of the portgroup file itself) should provide guidance on how each portgroup is used. Prospective MacPorts developers are also encouraged to examine existing portfiles that use these portgroups.