A Bit of Unix Typesetting History (Unix Power Tools, 3rd Edition)

45.11. A Bit of Unix Typesetting History

Unix was one of the first operating systems to provide the capability to drive a typesetter. troff is both a markup language and a tool for generating typesetter output.

Originally, troff was designed to drive a device called a C/A/T phototypesetter, and thus it generated a truly frightening collection of idiosyncratic commands. For a while, there were several version of troff and troff-related tools, including tools to translate C/A/T output into something useful, versions of troff that output slightly saner things than C/A/T, and so forth. It was all very confusing.

Most systems these days still have a version of troff, often GNU's groff, which outputs PostScript and other device-independent formats. Unix manpages are still written in nroff, a related tool that takes the same input and spits out ASCII-formatted text, using the man macro package. However, most people don't use troff and its related tools for general text formatting much any more.

So why do we care about troff? The Jargon Dictionary (Version 4.2.2) has this to say:

troff /T'rof/ or /trof/ n.

The gray eminence of Unix text processing; a formatting and phototypesetting program, written originally in PDP-11 assembler and then in barely-structured early C by the late Joseph Ossanna, modeled after the earlier ROFF which was in turn modeled after the Multics and CTSS program RUNOFF by Jerome Saltzer (that name came from the expression "to run off a copy"). A companion program, nroff, formats output for terminals and line printers.

In 1979, Brian Kernighan modified troff so that it could drive phototypesetters other than the Graphic Systems CAT. His paper describing that work ("A Typesetter-independent troff," AT&T CSTR #97) explains troff's durability. After discussing the program's "obvious deficiencies -- a rebarbative input syntax, mysterious and undocumented properties in some areas, and a voracious appetite for computer resources" and noting the ugliness and extreme hairiness of the code and internals, Kernighan concludes:

"None of these remarks should be taken as denigrating Ossanna's accomplishment with TROFF. It has proven a remarkably robust tool, taking unbelievable abuse from a variety of preprocessors and being forced into uses that were never conceived of in the original design, all with considerable grace under fire."

The success of T_EX and desktop publishing systems have reduced troff's relative importance, but this tribute perfectly captures the strengths that secured troff a place in hacker folklore; indeed, it could be taken more generally as an indication of those qualities of good programs that, in the long run, hackers most admire.

-- DJPH