> GFtoDVIand to will prompt you for a gf-filename. You may change some internal settings for this run by appending a slash to this filename and to will prompt you for ``special font substitutions,'' i.e., the replacement of `gray' or `black' fonts for a special output device. (See the `book' [4] for details.) Like most other programs, to is capable of accepting its arguments directly from the command line input, so you may type
> GFtoDVI cmr10.2602gf/and you will be prompted for further input.