usage: /usr/bin/pre-grohtml [-epV] [-a anti-aliasing-text-bits] [-D image-directory] [-F font-directory] [-g anti-aliasing-graphics-bits] [-i resolution] [-I image-stem] [-o image-vertical-offset] [-x html-dialect] troff-command troff-argument ...
usage: /usr/bin/pre-grohtml {-v | --version}
usage: /usr/bin/pre-grohtml --help

Prepare a troff(1) document for HTML formatting.

This program is not intended to be executed standalone; it is
normally part of a groff pipeline.  If your need to run it manually
(e.g., for debugging purposes), give the 'groff' program the
command-line option '-V' to inspect the arguments with which
'/usr/bin/pre-grohtml' is called.  See the grohtml(1) manual page.