In order to use variables like %%PREFIX%% (and get them expanded), use SUB_FILES and SUB_LIST in the port's Makefile.
SUB_LIST sets variables to be parsed, declared as VAR=VALUE:
SUB_LIST= ARCH=${ARCH}
Many variables are already set by default, including DATADIR, DOCSDIR, ETCDIR, EXAMPLESDIR, LOCALBASE, PREFIX and WWWDIR.
SUB_FILES specifies which files to be parsed.A typical example is pkg-message, which displays a message when the port/pkg is installed:
SUB_FILES= pkg-message
The templates must be placed in ${FILESDIR} (usually files/) and .in must be appended to the filenames.
Example: /usr/ports/dns/void-zones-tools/files/pkg-message.in:
To download the host lists and convert them to void zones, run the following script: %%PREFIX%%/bin/void-zones-update.sh To add your own white list/black list entries, to add over override the bundled listings, edit %%PREFIX%%/etc/void-zones/my_void_hosts.txt. Use the IP address 1.1.1.1 for whitelisting, and 0.0.0.0 for blacklisting. Add the following line to your unbound.conf, prior to any forwarder directives: include: /var/unbound/local-void.zones Then restart Unbound. For future updates, run void-zones-update.sh and restart Unbound. For more information, see %%PREFIX%%/share/doc/void-zones-tools/README.md or https://github.com/cyclaero/void-zones-tools
The resulting pkg-message will have %%PREFIX%% expanded to the actual prefix, which by default will be /usr/local.