Invoking groff (The GNU Troff Manual)

## 2 Invoking `groff`

This chapter focuses on how to invoke the `groff` front end. This front end takes care of the details of constructing the pipeline among the preprocessors, `gtroff` and the postprocessor.

It has become a tradition that GNU programs get the prefix ‘`g`’ to distinguish them from their original counterparts provided by the host (see Environment). Thus, for example, `geqn` is GNU `eqn`. On operating systems like GNU/Linux or the Hurd, which don’t contain proprietary versions of `troff`, and on MS-DOS/MS-Windows, where `troff` and associated programs are not available at all, this prefix is omitted since GNU `troff` is the only incarnation of `troff` used. Exception: ‘`groff`’ is never replaced by ‘`roff`’.

In this document, we consequently say ‘`gtroff`’ when talking about the GNU `troff` program. All other implementations of `troff` are called AT&T `troff`, which is the common origin of almost all `troff` implementations4 (with more or less compatible changes). Similarly, we say ‘`gpic`’, ‘`geqn`’, and so on.