The xlsfonts command will list the fonts installed on an X Window System. You can set it to see all fonts - but it will result in a large output - or you can shorten the output by combining wildcards with the fn pattern option.

Options:
* -l: Prints the information in a single column.
* -c: Prints the information in multiple columns.
* -fn pattern: Specifies the font pattern to search for.
* -1: Lists font attributes on one line.
* -11: Lists font properties in addition to -1 output.
* -111: Lists character metrics in addition to -11 output.
* -m: Lists minimum and maximum bounds of each font.
* -n columns: Sets the number of columns.
* -o: Performs OpenFont instead of ListFont.
* -u: Leaves output unsorted.
* -w width: Sets width in characters of the returned information.