A port is a distribution of software that can be compiled and
installed using MacPorts. A Portfile describes all
the required steps such as where to get the source code from upstream,
which patches have to be applied and which other tools and commands are
required to build the source code.
Each port consists of multiple files in a directory, usually within
a category subdirectory of the root of a ports tree. The MacPorts
Project distributes the main ports tree that is by default
configured
in all installations of MacPorts. This section serves as a reference for
the directory structure of a single port and the layout of the files
within. The only required file in a port is the
Portfile.
A MacPorts Portfile is a Tcl script that usually contains only the simple keyword/value combinations and Tcl extensions as described in the Portfile Reference chapter, though it may also contain arbitrary Tcl code. Every port has a corresponding Portfile, but Portfiles do not completely define a port's installation behavior since MacPorts base has default port installation characteristics coded within it. Therefore Portfiles need only specify required options, though some ports may require non-default options.
A common way for Portfiles to augment or override MacPorts base
default installation phase characteristics is by using
Portfile phase declaration(s). If you use Portfile
phase declaration(s), you should know how to identify the
“global” section of a Portfile. Any statements not contained
within a phase declaration, no matter where they are located in a Portfile,
are said to be in the global section of the Portfile; therefore the global
section need not be contiguous. Likewise, to remove statements from the
global section they must be placed within a phase declaration.
The main phases you need to be aware of when making a Portfile are these:
Fetch
Extract
Patch
Configure
Build
Destroot
The default installation phase behavior performed by the MacPorts base works fine for applications that use the standard configure, make, and make install steps, which conform to phases configure, build, and destroot respectively. For applications that do not conform to this standard behavior, any installation phase may be augmented using pre- and/or post- phases, or even overridden or eliminated. See Example Portfiles below.
For a detailed description of all port phases, see the Portfile Reference chapter.