xlsfonts [-display host:dpy] [-l] [-ll] [-lll] [-m] [-C] [-1] [-w width] [-n columns] [-u] [-o] [-fn pattern]
xlsfonts lists the fonts that match the given pattern. The wildcard character "*" may be used to match any sequence of characters (including none), and "?" to match any single character. If no pattern is given, "*" is assumed.
The "*" and "?" characters must be quoted to prevent them from being expanded by the shell.
X(7), Xserver(1), xset(1), xfd(1), X Logical Font Description Conventions
Doing ``xlsfonts -l'' can tie up your server for a very long time. This is really a bug with single-threaded non-preemptable servers, not with this program.