There are some tricks we have not mentioned yet about the pkg-* files that come in handy sometimes.
If you need to display a message to the installer, you may place the message in pkg-message. This capability is often useful to display additional installation steps to be taken after a pkg_add(1) or to display licensing information.
When some lines about the build-time knobs or warnings have to be displayed, use ECHO_MSG. The pkg-message file is only for post-installation steps. Likewise, the distinction between ECHO_MSG and ECHO_CMD should be kept in mind. The former is for printing informational text to the screen, while the latter is for command pipelining.
A good example for both can be found in shells/bash2/Makefile:
update-etc-shells:
@${ECHO_MSG} "updating /etc/shells"
@${CP} /etc/shells /etc/shells.bak
@( ${GREP} -v ${PREFIX}/bin/bash /etc/shells.bak; \
${ECHO_CMD} ${PREFIX}/bin/bash) >/etc/shells
@${RM} /etc/shells.bak
Note: The pkg-message file does not need to be added to pkg-plist. Also, it will not get automatically printed if the user is using the port, not the package, so you should probably display it from the post-install target yourself.