For a given port determine its dependences using any combination of the FETCH_, EXTRACT_, PATCH_, BUILD_, LIB_, and RUN_DEPENDS and show them as a pseudo graphical tree. Use back references for cross-connections. For example,

porttree /usr/ports/ports-mgmt/portdowngrade

prints the following.

0	┌ports-mgmt/portdowngrade
1	├┬devel/gmake
2	│└┬devel/gettext
3	│ ├┬converters/libiconv
4	│ │└devel/libtool
	│ └devel/libtool → 4
5	└┬devel/popt
	 ├┬converters/libiconv → 3
	 ├devel/libtool → 4
	 └┬devel/gettext → 2

Note the difference between two lines after line 5, both with back references. An additional pseudo graphical char before the port name in line refering to 3 indicates that devel/libiconv has at least one child. This is considered as a feature. In newer version, you can use -s 3 or -s 4 if you do not like the feature.

To see also all the ports depending on the given one, add -R to the command line. Always use -U filename (or -A -S filename if info is not yet saved) when you use -R.

Since the full scan of the ports tree (used with -A) is slow, -S filename will save the graph of the dependencies in a file filename. Further runs can use -U filename to load this saved information.

Defult style is to check the terminal for Alternative Cher Set (ACS) capability and use it if avalable, or fall back to text-only mode if ACS is not available. In console, you might use text style (add option -s 0 to the command line), or use | iconv -f utf-8 -t cp437 at the end of the command with -s 1 or -s 2. cp437 is correct code page for default screenmap, you might need to change that if you use another screenmap.

See more in man porttree.