groff (software)

Groff (GNU troff) is a typesetting system, part of the GNU project. It is an implementation of the older Unix troff command, itself derived from the runoff program. Groff reads one or more plain text files containing typesetting instructions and formatting requests and produces formatted output, typically in PostScript, PDF, or other formats. It is often used for creating documentation, manuals, and other types of formatted text.

Groff consists of a collection of programs. The groff command itself is a driver program that invokes other programs to perform the actual typesetting. Some key components include:

• troff: The core typesetting program. It interprets the typesetting instructions and generates intermediate output.
• eqn: A preprocessor for typesetting mathematical equations. It translates equation markup into troff instructions.
• tbl: A preprocessor for formatting tables. It translates table markup into troff instructions.
• pic: A preprocessor for drawing simple diagrams. It translates diagram markup into troff instructions.
• grops: A postprocessor for converting troff output to PostScript.
• groff_t: A general-purpose troff preprocessor

Groff uses a markup language consisting of requests and macros to control the formatting. Requests are built-in commands that specify actions like setting margins, indenting paragraphs, or changing fonts. Macros are collections of requests that can be used to perform more complex formatting tasks. Groff includes several macro packages, such as man for formatting manual pages, mdoc for formatting BSD-style manual pages, and ms for general-purpose document formatting.

Groff is widely used on Unix-like operating systems, including Linux and macOS. It is commonly employed for creating man pages, which are the standard form of documentation for Unix commands. Groff is a powerful and flexible typesetting system that can be used to create high-quality formatted documents. It provides a free and open-source alternative to commercial typesetting systems. Groff supports various output devices and has been extended over the years to include features such as Unicode support and improved PDF output.