If your port requires some configuration files in PREFIX/etc, do not just install them and list them in pkg-plist. That will cause pkg_delete(1) to delete files carefully edited by the user and a new installation to wipe them out.
Instead, install sample files with a suffix (filename.sample will work well). Copy the sample file as the real configuration file, if it does not exist. On deinstall, delete the configuration file, but only if it was not modified by the user. You need to handle this both in the port Makefile, and in the pkg-plist (for installation from the package).
Example of the Makefile part:
post-install:
@if [ ! -f ${PREFIX}/etc/orbit.conf ]; then \
${CP} -p ${PREFIX}/etc/orbit.conf.sample ${PREFIX}/etc/orbit.conf ; \
fi
Example of the pkg-plist part:
@unexec if cmp -s %D/etc/orbit.conf.sample %D/etc/orbit.conf; then rm -f %D/etc/orbit.conf; fi etc/orbit.conf.sample @exec if [ ! -f %D/etc/orbit.conf ] ; then cp -p %D/%F %B/orbit.conf; fi
Alternatively, print out a message pointing out that the user has to copy and edit the file before the software can be made to work.