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groff_diff - differences between GNU troff and classical troff




This manual page describes the language differences between groff, the GNU roff text processing system and the classical roff formatter of the freely available Unix~7 of the 1970s, documented in the Troff User’s Manual by Osanna and Kernighan. This inludes the roff language as well as the intermediate output format (troff output).

The section SEE ALSO gives pointers to both the classical roff and the modern groff documentation.


"Long names"


"Fractional pointsizes"

DESC file (1 by default).

"Numeric expressions"


"New escape sequences"


"New requests"

[dq]’)]*[rs](dg[rs](rq have this property). rgb (three components), cym (three components), cmyk (four components), and grey (one component). default (which is device-specific) can’t be redefined. char request (with an additional argument to specify the font); a glyph [rs]patterns{...} (possibly with whitespace before and after the braces). char request) nor translations (specified with the asciify request will use the character code (if any) before the character
.troff Make the n built-in condition false, and the t built-in condition true. This undoes the effect of the nroff request.
.unformat xx
This request ‘unformats’ the diversion xx. Contrary to the .asciify request, which tries to convert formatted elements of the diversion back to input tokens as much as possible, .unformat will only handle tabs and spaces between words (usually caused by spaces or newlines in the input) specially. The former are treated as if they were input tokens, and the latter are stretchable again. Note that the vertical size of lines is not preserved. Glyph information (font, font size, space width, etc.) is retained. Useful in conjunction with the .box and .boxa requests.
.vpt n Enable vertical position traps if n is non-zero, disable them otherwise. Vertical position traps are traps set by the wh or dt requests. Traps set by the it request are not vertical position traps. The parameter that controls whether vertical position traps are enabled is global. Initially vertical position traps are enabled.
.warn n Control warnings. n is the sum of the numbers associated with each warning that is to be enabled; all other warnings will be disabled. The number associated with each warning is listed in troff(1). For example, .warn~0 will disable all warnings, and .warn~1 will disable all warnings except that about missing glyphs. If n is not given, all warnings will be enabled.
.warnscale si
Set the scaling indicator used in warnings to si. Valid values for si are u, i, c, p, and P. At startup, it is set to~ i.
.while c anything
While condition~ c is true, accept anything as input; c~ can be any condition acceptable to an if request; anything can comprise multiple lines if the first line starts with [rs]{ and the last line ends with [rs]}. See also the break and continue requests.
.write stream anything
Write anything to the stream named stream. stream must previously have been the subject of an open request. anything is read in copy mode; a leading~ [dq] will be stripped.
.writec stream anything
Similar to write but without writing a final newline.
.writem stream xx
Write the contents of the macro or string xx to the stream named stream. stream must previously have been the subject of an open request. xx is read in copy mode.

"Extended escape sequences"

"Extended requests"

"New number registers"

troff(1). .psbb request and contain the bounding box values (in PostScript units) of a


troff predefines a single (read/write) string-based register,



"Text Commands"

"Drawing Commands"

"Device Control Commands"


"Groff Language"

"Intermediate Output"


troff(1). troff(1).


Thegroff info file, cf. info(1)presents all groff documentation within a single document.
A list of all documentation aroundgroff.
A description of thegroff language, including a short, but complete reference of all predefinedrequests, registers, and escapes of plaingroff. From the command line, this is called using
A survey ofroff systems, including pointers to further historical documentation.
TheNroff/\:Troff User’s Manual byJ. F. Osanna of 1976 in the revision ofBrian Kernighan of 1992, being the
"classical troff documentation" .


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