usage: /usr/bin/groff [-abcCeEgGijklNpRsStUVXzZ] [-d ctext] [-d string=text] [-D fallback-encoding] [-f font-family] [-F font-directory] [-I inclusion-directory] [-K input-encoding] [-L spooler-argument] [-m macro-package] [-M macro-directory] [-n page-number] [-o page-list] [-P postprocessor-argument] [-r cnumeric-expression] [-r register=numeric-expression] [-T output-device] [-w warning-category] [-W warning-category] [file ...]
usage: /usr/bin/groff {-v | --version}
usage: /usr/bin/groff {-h | --help}

groff (GNU roff) is a typesetting system that reads plain text input
files that include formatting commands to produce output in
PostScript, PDF, HTML, or DVI formats or for display to a terminal.
See the groff(1) manual page.