1GROFF(7) Miscellaneous Information Manual GROFF(7)
2
6 groff - a short reference for the GNU roff language
7
9 The name groff stands for GNU roff and is the free implementation of
10 the roff type-setting system. See roff(7) for a survey and the back‐
11 ground of the groff system.
12 This document gives only short descriptions of the predefined roff lan‐
14 guage elements as used in groff. Both the classical features and the
15 groff extensions are provided.
16 Historically, the roff language was called troff. groff is compatible
18 with the classical system and provides proper extensions. So in GNU,
19 the terms roff, troff, and groff language could be used as synonyms.
20 However troff slightly tends to refer more to the classical aspects,
21 whereas groff emphasizes the GNU extensions, and roff is the general
22 term for the language.
23 This file is only a short version of the complete documentation that is
25 found in the groff info(1) file, which contains more detailed, actual,
26 and concise information.
27 The general syntax for writing groff documents is relatively easy, but
29 writing extensions to the roff language can be a bit harder.
30 The roff language is line-oriented. There are only two kinds of lines,
32 control lines and text lines. The control lines start with a control
33 character, by default a period “.” or a single quote “'”; all other
34 lines are text lines.
35 Control lines represent commands, optionally with arguments. They have
37 the following syntax. The leading control character can be followed by
38 a command name; arguments, if any, are separated by spaces (but not tab
39 characters) from the command name and among themselves, for example,
40 .command_name arg1 arg2
42 For indentation, any number of space or tab characters can be inserted
44 between the leading control character and the command name, but the
45 control character must be on the first position of the line.
46 Text lines represent the parts that is printed. They can be modified
48 by escape sequences, which are recognized by a leading backslash ‘\’.
49 These are in-line or even in-word formatting elements or functions.
50 Some of these take arguments separated by single quotes “'”, others are
51 regulated by a length encoding introduced by an open parenthesis ‘(’ or
52 enclosed in brackets ‘[’ and ‘]’.
53 The roff language provides flexible instruments for writing language
55 extension, such as macros. When interpreting macro definitions, the
56 roff system enters a special operating mode, called the copy mode.
57 The copy mode behaviour can be quite tricky, but there are some rules
59 that ensure a safe usage.
60 1. Printable backslashes must be denoted as \e. To be more pre‐
62 cise, \e represents the current escape character. To get a
63 backslash glyph, use \(rs or \[rs].
64 2. Double all backslashes.
66 3. Begin all text lines with the special non-spacing character \&.
68 This does not produce the most efficient code, but it should work as a
70 first measure. For better strategies, see the groff info file and
71 groff_tmac(5).
72 Reading roff source files is easier, just reduce all double backslashes
74 to a single one in all macro definitions.
75
77 The roff language elements add formatting information to a text file.
78 The fundamental elements are predefined commands and variables that
79 make roff a full-blown programming language.
80 There are two kinds of roff commands, possibly with arguments.
82 Requests are written on a line of their own starting with a dot ‘.’ or
83 a “'”, whereas Escape sequences are in-line functions and in-word for‐
84 matting elements starting with a backslash ‘\’.
85 The user can define her own formatting commands using the de request.
87 These commands are called macros, but they are used exactly like
88 requests. Macro packages are pre-defined sets of macros written in the
89 groff language. A user's possibilities to create escape sequences her‐
90 self is very limited, only special characters can be mapped.
91 The groff language provides several kinds of variables with different
93 interfaces. There are pre-defined variables, but the user can define
94 her own variables as well.
95 String variables store character sequences. They are set with the ds
97 request and retrieved by the \* escape sequences. Strings can have
98 variables.
99 Register variables can store numerical values, numbers with a scale
101 unit, and occasionally string-like objects. They are set with the nr
102 request and retrieved by the \n escape sequences.
103 Environments allow the user to temporarily store global formatting
105 parameters like line length, font size, etc. for later reuse. This is
106 done by the ev request.
107 Fonts are identified either by a name or by an internal number. The
109 current font is chosen by the ft request or by the \f escape sequences.
110 Each device has special fonts, but the following fonts are available
111 for all devices. R is the standard font Roman. B is its bold counter‐
112 part. The italic font is called I and is available everywhere, but on
113 text devices it is displayed as an underlined Roman font. For the
114 graphical output devices, there exist constant-width pendants of these
115 fonts, CR, CI, and CB. On text devices, all glyphs have a constant
116 width anyway.
117 Glyphs are visual representation forms of characters. In groff, the
119 distinction between those two elements is not always obvious (and a
120 full discussion is beyond the scope of this man page). A first approx‐
121 imation is that glyphs have a specific size and colour and are taken
122 from a specific font; they can't be modified any more – characters are
123 the input, and glyphs are the output. As soon as an output line has
124 been generated, it no longer contains characters but glyphs. In this
125 man page, we use either ‘glyph’ or ‘character’, whatever is more appro‐
126 priate.
127 Moreover, there are some advanced roff elements. A diversion stores
129 (formatted) information into a macro for later usage. A trap is a
130 positional condition like a certain number of lines from page top or in
131 a diversion or in the input. Some action can be prescribed to be run
132 automatically when the condition is met.
133 More detailed information and examples can be found in the groff info
135 file.
136
138 There is a small set of characters that have a special controlling task
139 in certain conditions.
140 . A dot is only special at the beginning of a line or after the
142 condition in the requests if, ie, el, and while. There it is
143 the control character that introduces a request (or macro). By
144 using the cc request, the control character can be set to a dif‐
145 ferent character, making the dot ‘.’ a non-special character.
146 In all other positions, it just means a dot character. In text
148 paragraphs, it is advantageous to start each sentence at a line
149 of its own.
150 ' The single quote has two controlling tasks. At the beginning of
152 a line and in the conditional requests it is the non-breaking
153 control character. That means that it introduces a request like
154 the dot, but with the additional property that this request
155 doesn't cause a linebreak. By using the c2 request, the non-
156 break control character can be set to a different character.
157 As a second task, it is the most commonly used argument separa‐
159 tor in some functional escape sequences (but any pair of charac‐
160 ters not part of the argument do work). In all other positions,
161 it denotes the single quote or apostrophe character. Groff pro‐
162 vides a printable representation with the \(cq escape sequence.
163 " The double quote is used to enclose arguments in macros (but not
165 in requests and strings). In the ds and as requests, a leading
166 double quote in the argument is stripped off, making everything
167 else afterwards the string to be defined (enabling leading
168 whitespace). The escaped double quote \" introduces a comment.
169 Otherwise, it is not special. Groff provides a printable repre‐
170 sentation with the \(dq escape sequence.
171 \ The backslash usually introduces an escape sequence (this can be
173 changed with the ec request). A printed version of the escape
174 character is the \e escape; a backslash glyph can be obtained by
175 \(rs.
176 ( The open parenthesis is only special in escape sequences when
178 introducing an escape name or argument consisting of exactly two
179 characters. In groff, this behaviour can be replaced by the []
180 construct.
181 [ The opening bracket is only special in groff escape sequences;
183 there it is used to introduce a long escape name or long escape
184 argument. Otherwise, it is non-special, e.g. in macro calls.
185 ] The closing bracket is only special in groff escape sequences;
187 there it terminates a long escape name or long escape argument.
188 Otherwise, it is non-special.
189 space Space characters are only functional characters. They separate
191 the arguments in requests, macros, and strings, and the words in
192 text lines. They are subject to groff's horizontal spacing cal‐
193 culations. To get a defined space width, escape sequences like
194 ‘\ ’ (this is the escape character followed by a space), \|, \^,
195 or \h should be used.
196 newline
198 In text paragraphs, newlines mostly behave like space charac‐
199 ters. Continuation lines can be specified by an escaped new‐
200 line, i.e., by specifying a backslash ‘\’ as the last character
201 of a line.
202 tab If a tab character occurs during text the interpreter makes a
204 horizontal jump to the next pre-defined tab position. There is
205 a sophisticated interface for handling tab positions.
206
208 A numerical value is a signed or unsigned integer or float with or
209 without an appended scaling indicator. A scaling indicator is a one-
210 character abbreviation for a unit of measurement. A number followed by
211 a scaling indicator signifies a size value. By default, numerical val‐
212 ues do not have a scaling indicator, i.e., they are normal numbers.
213 The roff language defines the following scaling indicators.
215 c Centimeter
217 i Inch
218 P Pica = 1/6 inch
219 p Point = 1/72 inch
220 m Em = the font size in points (approx. width of letter
221 ‘m’)
222 M 100th of an Em
223 n En = Em/2
224 u Basic unit for actual output device
225 v Vertical line space in basic units scaled
226 point = 1/sizescale of a point (defined in font DESC
227 file)
228 f Scale by 65536.
229 Numerical expressions are combinations of the numerical values defined
231 above with the following arithmetical operators already defined in
232 classical troff.
233 + Addition
235 - Subtraction
236 * Multiplication
237 / Division
238 % Modulo
239 = Equals
240 == Equals
241 < Less than
242 > Greater than
243 <= Less or equal
244 >= Greater or equal
245 & Logical and
246 : Logical or
247 ! Logical not
248 ( Grouping of expressions
249 ) Close current grouping
250 Moreover, groff added the following operators for numerical expres‐
252 sions:
253 e1>?e2 The maximum of e1 and e2.
255 e1<?e2 The minimum of e1 and e2.
256 (c;e) Evaluate e using c as the default scaling indicator.
257 For details see the groff info file.
259
261 Conditions occur in tests raised by the if, ie, and the while requests.
262 The following table characterizes the different types of conditions.
263 N A numerical expression N yields true if its value is
265 greater than 0.
266 !N True if the value of N is 0 (see below).
267 's1's2' True if string s1 is identical to string s2.
268 !'s1's2' True if string s1 is not identical to string s2 (see
269 below).
270 cch True if there is a glyph ch available.
271 dname True if there is a string, macro, diversion, or
272 request called name.
273 e Current page number is even.
274 o Current page number is odd.
275 mname True if there is a color called name.
276 n Formatter is nroff.
277 rreg True if there is a register named reg.
278 t Formatter is troff.
279 Ffont True if there exists a font named font.
280 Sstyle True if a style named style has been registered.
281 Note that the ! operator may only appear at the beginning of an
283 expression, and negates the entire expression. This maintains bug-com‐
284 patibility with AT&T troff.
285
287 This section provides a short reference for the predefined requests.
288 In groff, request, macro, and string names can be arbitrarily long. No
289 bracketing or marking of long names is needed.
290 Most requests take one or more arguments. The arguments are separated
292 by space characters (no tabs!); there is no inherent limit for their
293 length or number.
294 Some requests have optional arguments with a different behaviour. Not
296 all of these details are outlined here. Refer to the groff info file
297 and groff_diff(7) for all details.
298 In the following request specifications, most argument names were cho‐
300 sen to be descriptive. Only the following denotations need clarifica‐
301 tion.
302 c denotes a single character.
304 font a font either specified as a font name or a font num‐
305 ber.
306 anything all characters up to the end of the line or within \{
307 and \}.
308 n is a numerical expression that evaluates to an integer
309 value.
310 N is an arbitrary numerical expression, signed or
311 unsigned.
312 ±N has three meanings depending on its sign, described
313 below.
314 If an expression defined as ±N starts with a ‘+’ sign the resulting
316 value of the expression is added to an already existing value inherent
317 to the related request, e.g. adding to a number register. If the
318 expression starts with a ‘-’ the value of the expression is subtracted
319 from the request value.
320 Without a sign, N replaces the existing value directly. To assign a
322 negative number either prepend 0 or enclose the negative number in
323 parentheses.
324 Request Short Reference
326 . Empty line, ignored. Useful for structuring documents.
327 .\" anything
328 Complete line is a comment.
329 .ab string
330 Print string on standard error, exit program.
331 .ad Begin line adjustment for output lines in current adjust
332 mode.
333 .ad c Start line adjustment in mode c (c=l,r,c,b,n).
334 .af register c
335 Assign format c to register (c=l,i,I,a,A).
336 .aln alias register
337 Create alias name for register.
338 .als alias object
339 Create alias name for request, string, macro, or diversion
340 object.
341 .am macro Append to macro until .. is encountered.
342 .am macro end
343 Append to macro until .end is called.
344 .am1 macro
345 Same as .am but with compatibility mode switched off during
346 macro expansion.
347 .am1 macro end
348 Same as .am but with compatibility mode switched off during
349 macro expansion.
350 .ami macro
351 Append to a macro whose name is contained in the string reg‐
352 ister macro until .. is encountered.
353 .ami macro end
354 Append to a macro indirectly. macro and end are string reg‐
355 isters whose contents are interpolated for the macro name and
356 the end macro, respectively.
357 .ami1 macro
358 Same as .ami but with compatibility mode switched off during
359 macro expansion.
360 .ami1 macro end
361 Same as .ami but with compatibility mode switched off during
362 macro expansion.
363 .as stringvar anything
364 Append anything to stringvar.
365 .as1 stringvar anything
366 Same as .as but with compatibility mode switched off during
367 string expansion.
368 .asciify diversion
369 Unformat ASCII characters, spaces, and some escape sequences
370 in diversion.
371 .backtrace
372 Print a backtrace of the input on stderr.
373 .bd font N
374 Embolden font by N-1 units.
375 .bd S font N
376 Embolden Special Font S when current font is font.
377 .blm Unset the blank line macro.
378 .blm macro
379 Set the blank line macro to macro.
380 .box End current diversion.
381 .box macro
382 Divert to macro, omitting a partially filled line.
383 .boxa End current diversion.
384 .boxa macro
385 Divert and append to macro, omitting a partially filled line.
386 .bp Eject current page and begin new page.
387 .bp ±N Eject current page; next page number ±N.
388 .br Line break.
389 .brp Break and spread output line. Same as \p.
390 .break Break out of a while loop.
391 .c2 Reset no-break control character to “'”.
392 .c2 c Set no-break control character to c.
393 .cc Reset control character to ‘.’.
394 .cc c Set control character to c.
395 .ce Center the next input line.
396 .ce N Center following N input lines.
397 .cf filename
398 Copy contents of file filename unprocessed to stdout or to
399 the diversion.
400 .cflags mode c1 c2 ...
401 Treat characters c1, c2, ... according to mode number.
402 .ch trap N
403 Change trap location to N.
404 .char c anything
405 Define entity c as string anything.
406 .chop object
407 Chop the last character off macro, string, or diversion
408 object.
409 .class name c1 c2 ...
410 Assign a set of characters, character ranges, or classes c1,
411 c2, ... to name.
412 .close stream
413 Close the stream.
414 .color Enable colors.
415 .color N If N is zero disable colors, otherwise enable them.
416 .composite from to
417 Map glyph name from to glyph name to while constructing a
418 composite glyph name.
419 .continue Finish the current iteration of a while loop.
420 .cp Enable compatibility mode.
421 .cp N If N is zero disable compatibility mode, otherwise enable it.
422 .cs font N M
423 Set constant character width mode for font to N/36 ems with
424 em M.
425 .cu N Continuous underline in nroff, like .ul in troff.
426 .da End current diversion.
427 .da macro Divert and append to macro.
428 .de macro Define or redefine macro until .. is encountered.
429 .de macro end
430 Define or redefine macro until .end is called.
431 .de1 macro
432 Same as .de but with compatibility mode switched off during
433 macro expansion.
434 .de1 macro end
435 Same as .de but with compatibility mode switched off during
436 macro expansion.
437 .defcolor color scheme component
438 Define or redefine a color with name color. scheme can be
439 rgb, cym, cymk, gray, or grey. component can be single com‐
440 ponents specified as fractions in the range 0 to 1 (default
441 scaling indicator f), as a string of two-digit hexadecimal
442 color components with a leading #, or as a string of four-
443 digit hexadecimal components with two leading #. The color
444 default can't be redefined.
445 .dei macro
446 Define or redefine a macro whose name is contained in the
447 string register macro until .. is encountered.
448 .dei macro end
449 Define or redefine a macro indirectly. macro and end are
450 string registers whose contents are interpolated for the
451 macro name and the end macro, respectively.
452 .dei1 macro
453 Same as .dei but with compatibility mode switched off during
454 macro expansion.
455 .dei1 macro end
456 Same as .dei but with compatibility mode switched off during
457 macro expansion.
458 .device anything
459 Write anything to the intermediate output as a device control
460 function.
461 .devicem name
462 Write contents of macro or string name uninterpreted to the
463 intermediate output as a device control function.
464 .di End current diversion.
465 .di macro Divert to macro.
466 .do name Interpret .name with compatibility mode disabled.
467 .ds stringvar anything
468 Set stringvar to anything.
469 .ds1 stringvar anything
470 Same as .ds but with compatibility mode switched off during
471 string expansion.
472 .dt N trap
473 Set diversion trap to position N (default scaling indica‐
474 tor v).
475 .ec Reset escape character to ‘\’.
476 .ec c Set escape character to c.
477 .ecr Restore escape character saved with .ecs.
478 .ecs Save current escape character.
479 .el anything
480 Else part for if-else (ie) request.
481 .em macro The macro is run after the end of input.
482 .eo Turn off escape character mechanism.
483 .ev Switch to previous environment and pop it off the stack.
484 .ev env Push down environment number or name env to the stack and
485 switch to it.
486 .evc env Copy the contents of environment env to the current environ‐
487 ment. No pushing or popping.
488 .ex Exit from roff processing.
489 .fam Return to previous font family.
490 .fam name Set the current font family to name.
491 .fc Disable field mechanism.
492 .fc a Set field delimiter to a and pad glyph to space.
493 .fc a b Set field delimiter to a and pad glyph to b.
494 .fchar c anything
495 Define fallback character (or glyph) c as string anything.
496 .fcolor Set fill color to previous fill color.
497 .fcolor c Set fill color to c.
498 .fi Fill output lines.
499 .fl Flush output buffer.
500 .fp n font
501 Mount font on position n.
502 .fp n internal external
503 Mount font with long external name to short internal name on
504 position n.
505 .fschar f c anything
506 Define fallback character (or glyph) c for font f as string
507 anything.
508 .fspecial font
509 Reset list of special fonts for font to be empty.
510 .fspecial font s1 s2 ...
511 When the current font is font, then the fonts s1, s2, ... are
512 special.
513 .ft Return to previous font. Same as \f[] or \fP.
514 .ft font Change to font name or number font; same as \f[font] escape
515 sequence.
516 .ftr font1 font2
517 Translate font1 to font2.
518 .fzoom font
519 Don't magnify font.
520 .fzoom font zoom
521 Set zoom factor for font (in multiples of 1/1000th).
522 .gcolor Set glyph color to previous glyph color.
523 .gcolor c Set glyph color to c.
524 .hc Remove additional hyphenation indicator character.
525 .hc c Set up additional hyphenation indicator character c.
526 .hcode c1 code1 c2 code2 ...
527 Set the hyphenation code of character c1 to code1, that of c2
528 to code2, etc.
529 .hla lang Set the current hyphenation language to lang.
530 .hlm n Set the maximum number of consecutive hyphenated lines to n.
531 .hpf file Read hyphenation patterns from file.
532 .hpfa file
533 Append hyphenation patterns from file.
534 .hpfcode a b c d ...
535 Set input mapping for .hpf.
536 .hw words List of words with exceptional hyphenation.
537 .hy N Switch to hyphenation mode N.
538 .hym n Set the hyphenation margin to n (default scaling indica‐
539 tor m).
540 .hys n Set the hyphenation space to n.
541 .ie cond anything
542 If cond then anything else goto .el.
543 .if cond anything
544 If cond then anything; otherwise do nothing.
545 .ig Ignore text until .. is encountered.
546 .ig end Ignore text until .end is called.
547 .in Change to previous indentation value.
548 .in ±N Change indentation according to ±N (default scaling indica‐
549 tor m).
550 .it N trap
551 Set an input-line count trap for the next N lines.
552 .itc N trap
553 Same as .it but count lines interrupted with \c as one line.
554 .kern Enable pairwise kerning.
555 .kern n If n is zero, disable pairwise kerning, otherwise enable it.
556 .lc Remove leader repetition glyph.
557 .lc c Set leader repetition glyph to c.
558 .length register anything
559 Write the length of the string anything to register.
560 .linetabs Enable line-tabs mode (i.e., calculate tab positions relative
561 to output line).
562 .linetabs n
563 If n is zero, disable line-tabs mode, otherwise enable it.
564 .lf N Set input line number to N.
565 .lf N file
566 Set input line number to N and filename to file.
567 .lg N Ligature mode on if N>0.
568 .ll Change to previous line length.
569 .ll ±N Set line length according to ±N (default length 6.5i, default
570 scaling indicator m).
571 .lsm Unset the leading spaces macro.
572 .lsm macro
573 Set the leading spaces macro to macro.
574 .ls Change to the previous value of additional intra-line skip.
575 .ls N Set additional intra-line skip value to N, i.e., N-1 blank
576 lines are inserted after each text output line.
577 .lt ±N Length of title (default scaling indicator m).
578 .mc Margin glyph off.
579 .mc c Print glyph c after each text line at actual distance from
580 right margin.
581 .mc c N Set margin glyph to c and distance to N from right margin
582 (default scaling indicator m).
583 .mk register
584 Mark current vertical position in register.
585 .mso file The same as .so except that file is searched in the tmac
586 directories.
587 .na No output-line adjusting.
588 .ne Need a one-line vertical space.
589 .ne N Need N vertical space (default scaling indicator v).
590 .nf No filling or adjusting of output-lines.
591 .nh No hyphenation.
592 .nm Number mode off.
593 .nm ±N [M [S [I]]]
594 In line number mode, set number, multiple, spacing, and
595 indentation.
596 .nn Do not number next line.
597 .nn N Do not number next N lines.
598 .nop anything
599 Always process anything.
600 .nr register ±N [M]
601 Define or modify register using ±N with auto-increment M.
602 .nroff Make the built-in conditions n true and t false.
603 .ns Turn on no-space mode.
604 .nx Immediately jump to end of current file.
605 .nx filename
606 Immediately continue processing with file file.
607 .open stream filename
608 Open filename for writing and associate the stream named
609 stream with it.
610 .opena stream filename
611 Like .open but append to it.
612 .os Output vertical distance that was saved by the sv request.
613 .output string
614 Emit string directly to intermediate output, allowing leading
615 whitespace if string starts with " (which is stripped off).
616 .pc Reset page number character to ‘%’.
617 .pc c Page number character.
618 .pev Print the current environment and each defined environment
619 state to stderr.
620 .pi program
621 Pipe output to program (nroff only).
622 .pl Set page length to default 11i. The current page length is
623 stored in register .p.
624 .pl ±N Change page length to ±N (default scaling indicator v).
625 .pm Print macro names and sizes (number of blocks of 128 bytes).
626 .pm t Print only total of sizes of macros (number of 128 bytes
627 blocks).
628 .pn ±N Next page number N.
629 .pnr Print the names and contents of all currently defined number
630 registers on stderr.
631 .po Change to previous page offset. The current page offset is
632 available in register .o.
633 .po ±N Page offset N.
634 .ps Return to previous point size.
635 .ps ±N Point size; same as \s[±N].
636 .psbb filename
637 Get the bounding box of a PostScript image filename.
638 .pso command
639 This behaves like the so request except that input comes from
640 the standard output of command.
641 .ptr Print the names and positions of all traps (not including
642 input line traps and diversion traps) on stderr.
643 .pvs Change to previous post-vertical line spacing.
644 .pvs ±N Change post-vertical line spacing according to ±N (default
645 scaling indicator p).
646 .rchar c1 c2 ...
647 Remove the definitions of entities c1, c2, ...
648 .rd prompt
649 Read insertion.
650 .return Return from a macro.
651 .return anything
652 Return twice, namely from the macro at the current level and
653 from the macro one level higher.
654 .rfschar f c1 c2 ...
655 Remove the definitions of entities c1, c2, ... for font f.
656 .rj n Right justify the next n input lines.
657 .rm name Remove request, macro, or string name.
658 .rn old new
659 Rename request, macro, or string old to new.
660 .rnn reg1 reg2
661 Rename register reg1 to reg2.
662 .rr register
663 Remove register.
664 .rs Restore spacing; turn no-space mode off.
665 .rt ±N Return (upward only) to marked vertical place (default scal‐
666 ing indicator v).
667 .schar c anything
668 Define global fallback character (or glyph) c as string any‐
669 thing.
670 .shc Reset soft hyphen glyph to \(hy.
671 .shc c Set the soft hyphen glyph to c.
672 .shift n In a macro, shift the arguments by n positions.
673 .sizes s1 s2 ... sn [0]
674 Set available font sizes similar to the sizes command in a
675 DESC file.
676 .so filename
677 Include source file.
678 .sp Skip one line vertically.
679 .sp N Space vertical distance N up or down according to sign of N
680 (default scaling indicator v).
681 .special Reset global list of special fonts to be empty.
682 .special s1 s2 ...
683 Fonts s1, s2, etc. are special and are searched for glyphs
684 not in the current font.
685 .spreadwarn
686 Toggle the spread warning on and off without changing its
687 value.
688 .spreadwarn limit
689 Emit a warning if each space in an output line is widened by
690 limit or more (default scaling indicator m).
691 .ss N Set space glyph size to N/12 of the space width in the cur‐
692 rent font.
693 .ss N M Set space glyph size to N/12 and sentence space size set to
694 M/12 of the space width in the current font.
695 .sty n style
696 Associate style with font position n.
697 .substring xx n1 n2
698 Replace the string named xx with the substring defined by the
699 indices n1 and n2.
700 .sv Save 1 v of vertical space.
701 .sv N Save the vertical distance N for later output with os request
702 (default scaling indicator v).
703 .sy command-line
704 Execute program command-line.
705 .ta T N Set tabs after every position that is a multiple of N
706 (default scaling indicator m).
707 .ta n1 n2 ... nn T r1 r2 ... rn
708 Set tabs at positions n1, n2, ..., nn, then set tabs at
709 nn+r1, nn+r2, ..., nn+rn, then at nn+rn+r1, nn+rn+r2, ...,
710 nn+rn+rn, and so on.
711 .tc Remove tab repetition glyph.
712 .tc c Set tab repetition glyph to c.
713 .ti ±N Temporary indent next line (default scaling indicator m).
714 .tkf font s1 n1 s2 n2
715 Enable track kerning for font.
716 .tl ’left’center’right’
717 Three-part title.
718 .tm anything
719 Print anything on stdout.
720 .tm1 anything
721 Print anything on stdout, allowing leading whitespace if any‐
722 thing starts with " (which is stripped off).
723 .tmc anything
724 Similar to .tm1 without emitting a final newline.
725 .tr abcd...
726 Translate a to b, c to d, etc. on output.
727 .trf filename
728 Transparently output the contents of file filename.
729 .trin abcd...
730 This is the same as the tr request except that the asciify
731 request uses the character code (if any) before the character
732 translation.
733 .trnt abcd...
734 This is the same as the tr request except that the transla‐
735 tions do not apply to text that is transparently throughput
736 into a diversion with \!.
737 .troff Make the built-in conditions t true and n false.
738 .uf font Set underline font to font (to be switched to by .ul).
739 .ul N Underline (italicize in troff) N input lines.
740 .unformat diversion
741 Unformat space characters and tabs in diversion, preserving
742 font information.
743 .vpt n Enable vertical position traps if n is non-zero, disable them
744 otherwise.
745 .vs Change to previous vertical base line spacing.
746 .vs ±N Set vertical base line spacing to ±N (default scaling indica‐
747 tor p).
748 .warn n Set warnings code to n.
749 .warnscale si
750 Set scaling indicator used in warnings to si.
751 .wh N Remove (first) trap at position N.
752 .wh N trap
753 Set location trap; negative means from page bottom.
754 .while cond anything
755 While condition cond is true, accept anything as input.
756 .write stream anything
757 Write anything to the stream named stream.
758 .writec stream anything
759 Similar to .write without emitting a final newline.
760 .writem stream xx
761 Write contents of macro or string xx to the stream named
762 stream.
763 Besides these standard groff requests, there might be further macro
765 calls. They can originate from a macro package (see roff(7) for an
766 overview) or from a preprocessor.
767 Preprocessor macros are easy to be recognized. They enclose their code
769 into a pair of characteristic macros.
770 ┌─────────────┬─────────────────┬────────────────┐
772 │preprocessor │ start macro │ end macro │
773 ├─────────────┼─────────────────┼────────────────┤
774 │ chem │ .cstart │ .cend │
775 │ eqn │ .EQ │ .EN │
776 │ gideal │ .IS │ .IE │
777 │ grap │ .G1 │ .G2 │
778 │ grn │ .GS │ .GE │
779 │ │ │ .IF │
780 │ pic │ .PS │ .PE │
781 │ refer │ .R1 │ .R2 │
782 │ soelim │ none │ none │
783 │ tbl │ .TS │ .TE │
784 ├─────────────┼─────────────────┼────────────────┤
785 │ glilypond │ .lilypond start │ .lilypond stop │
786 │ gperl │ .Perl start │ .Perl stop │
787 │ gpinyin │ .pinyin start │ .pinyin stop │
788 └─────────────┴─────────────────┴────────────────┘
789 Note that the ‘ideal’ preprocessor is not available in groff yet.
790
792 Escape sequences are in-line language elements usually introduced by a
793 backslash ‘\’ and followed by an escape name and sometimes by a
794 required argument. Input processing is continued directly after the
795 escaped character or the argument (without an intervening separation
796 character). So there must be a way to determine the end of the escape
797 name and the end of the argument.
798 This is done by enclosing names (escape name and arguments consisting
800 of a variable name) by a pair of brackets [name] and constant arguments
801 (number expressions and characters) by apostrophes (ASCII 0x27) like
802 ’constant’.
803 There are abbreviations for short names. Two-character escape names
805 can be specified by an opening parenthesis like \(xy or \*(xy without a
806 closing counterpart. And all one-character names different from the
807 special characters ‘[’ and ‘(’ can even be specified without a marker,
808 for example \nc or \$c.
809 Constant arguments of length 1 can omit the marker apostrophes, too,
811 but there is no two-character analogue.
812 While one-character escape sequences are mainly used for in-line func‐
814 tions and system related tasks, the two-letter names following the \(
815 construct are glyphs predefined by the roff system; these are called
816 ‘Special Characters’ in the classical documentation. Escapes sequences
817 of the form \[name] denote glyphs too.
818 Single-Character Escapes
820 \" Start of a comment. Everything up to the end of the line is
821 ignored.
822 \# Everything up to and including the next newline is ignored.
823 This is interpreted in copy mode. This is like \" except that
824 the terminating newline is ignored as well.
825 \*s The string stored in the string variable with one-character
826 name s.
827 \*(st The string stored in the string variable with two-character name
828 st.
829 \*[string]
830 The string stored in the string variable with name string (with
831 arbitrary length).
832 \*[stringvar arg1 arg2 ...]
833 The string stored in the string variable with arbitrarily long
834 name stringvar, taking arg1, arg2, ... as arguments.
835 \$0 The name by which the current macro was invoked. The als
836 request can make a macro have more than one name.
837 \$x Macro or string argument with one-digit number x in the range 1
838 to 9.
839 \$(xy Macro or string argument with two-digit number xy (larger than
840 zero).
841 \$[nexp]
842 Macro or string argument with number nexp, where nexp is a
843 numerical expression evaluating to an integer ≥1.
844 \$* In a macro or string, the concatenation of all the arguments
845 separated by spaces.
846 \$@ In a macro or string, the concatenation of all the arguments
847 with each surrounded by double quotes, and separated by spaces.
848 \$^ In a macro, the representation of all parameters as if they were
849 an argument to the ds request.
850 \\ reduces to a single backslash; useful to delay its interpreta‐
851 tion as escape character in copy mode. For a printable back‐
852 slash, use \e, or even better \[rs], to be independent from the
853 current escape character.
854 \´ The acute accent ´; same as \(aa. Unescaped: apostrophe, right
855 quotation mark, single quote (ASCII 0x27).
856 \` The grave accent `; same as \(ga. Unescaped: left quote, back‐
857 quote (ASCII 0x60).
858 \- The - (minus) sign in the current font.
859 \_ The same as \(ul, the underline character.
860 \. The same as a dot (‘.’). Necessary in nested macro definitions
861 so that ‘\\..’ expands to ‘..’.
862 \% Default optional hyphenation character.
863 \! Transparent line indicator.
864 \?anything?
865 In a diversion, this transparently embeds anything in the diver‐
866 sion. anything is read in copy mode. See also the escape
867 sequences \! and \?.
868 \space Unpaddable space size space glyph (no line break).
869 \0 Digit-width space.
870 \| 1/6 em narrow space glyph; zero width in nroff.
871 \^ 1/12 em half-narrow space glyph; zero width in nroff.
872 \& Non-printable, zero-width glyph.
873 \) Like \& except that it behaves like a glyph declared with the
874 cflags request to be transparent for the purposes of end-of-sen‐
875 tence recognition.
876 \/ Increases the width of the preceding glyph so that the spacing
877 between that glyph and the following glyph is correct if the
878 following glyph is a roman glyph.
879 \, Modifies the spacing of the following glyph so that the spacing
880 between that glyph and the preceding glyph is correct if the
881 preceding glyph is a roman glyph.
882 \~ Unbreakable space that stretches like a normal inter-word space
883 when a line is adjusted.
884 \: Inserts a zero-width break point (similar to \% but without a
885 soft hyphen character).
886 \newline
887 Ignored newline, for continuation lines.
888 \{ Begin conditional input.
889 \} End conditional input.
890 \(sc A glyph with two-character name sc; see section Special Charac‐
891 ters.
892 \[name]
893 A glyph with name name (of arbitrary length).
894 \[comp1 comp2 ...]
895 A composite glyph with components comp1, comp2, ...
896 \a Non-interpreted leader character.
897 \A’anything’
898 If anything is acceptable as a name of a string, macro, diver‐
899 sion, register, environment or font it expands to 1, and to 0
900 otherwise.
901 \b’abc...’
902 Bracket building function.
903 \B’anything’
904 If anything is acceptable as a valid numeric expression it
905 expands to 1, and to 0 otherwise.
906 \c Interrupt text processing.
907 \C’glyph’
908 The glyph called glyph; same as \[glyph], but compatible to
909 other roff versions.
910 \d Forward (down) 1/2 em (1/2 line in nroff).
911 \D’charseq’
912 Draw a graphical element defined by the characters in charseq;
913 see the groff info file for details.
914 \e Printable version of the current escape character.
915 \E Equivalent to an escape character, but is not interpreted in
916 copy mode.
917 \fF Change to font with one-character name or one-digit number F.
918 \fP Switch back to previous font.
919 \f(fo Change to font with two-character name or two-digit number fo.
920 \f[font]
921 Change to font with arbitrarily long name or number expression
922 font.
923 \f[] Switch back to previous font.
924 \Ff Change to font family with one-character name f.
925 \F(fm Change to font family with two-character name fm.
926 \F[fam]
927 Change to font family with arbitrarily long name fam.
928 \F[] Switch back to previous font family.
929 \gr Return format of register with one-character name r suitable for
930 af request.
931 \g(rg Return format of register with two-character name rg suitable
932 for af request.
933 \g[reg]
934 Return format of register with arbitrarily long name reg suit‐
935 able for af request.
936 \h’N’ Local horizontal motion; move right N (left if negative).
937 \H’N’ Set height of current font to N.
938 \kr Mark horizontal input place in one-character register r.
939 \k(rg Mark horizontal input place in two-character register rg.
940 \k[reg]
941 Mark horizontal input place in register with arbitrarily long
942 name reg.
943 \l’Nc’ Horizontal line drawing function (optionally using character c).
944 \L’Nc’ Vertical line drawing function (optionally using character c).
945 \mc Change to color with one-character name c.
946 \m(cl Change to color with two-character name cl.
947 \m[color]
948 Change to color with arbitrarily long name color.
949 \m[] Switch back to previous color.
950 \Mc Change filling color for closed drawn objects to color with one-
951 character name c.
952 \M(cl Change filling color for closed drawn objects to color with two-
953 character name cl.
954 \M[color]
955 Change filling color for closed drawn objects to color with
956 arbitrarily long name color.
957 \M[] Switch to previous fill color.
958 \nr The numerical value stored in the register variable with the
959 one-character name r.
960 \n(re The numerical value stored in the register variable with the
961 two-character name re.
962 \n[reg]
963 The numerical value stored in the register variable with arbi‐
964 trarily long name reg.
965 \N’n’ Typeset the glyph with index n in the current font. No special
966 fonts are searched. Useful for adding (named) entities to a
967 document using the char request and friends.
968 \o’abc...’
969 Overstrike glyphs a, b, c, etc.
970 \O0 Disable glyph output. Mainly for internal use.
971 \O1 Enable glyph output. Mainly for internal use.
972 \p Break and spread output line.
973 \r Reverse 1 em vertical motion (reverse line in nroff).
974 \R’name ±n’
975 The same as .nr name ±n.
976 \s±N Set/increase/decrease the point size to/by N scaled points; N is
977 a one-digit number in the range 1 to 9. Same as ps request.
978 \s(±N
979 \s±(N Set/increase/decrease the point size to/by N scaled points; N is
980 a two-digit number ≥1. Same as ps request.
981 \s[±N]
982 \s±[N]
983 \s’±N’
984 \s±’N’ Set/increase/decrease the point size to/by N scaled points.
985 Same as ps request.
986 \S’N’ Slant output by N degrees.
987 \t Non-interpreted horizontal tab.
988 \u Reverse (up) 1/2 em vertical motion (1/2 line in nroff).
989 \v’N’ Local vertical motion; move down N (up if negative).
990 \Ve The contents of the environment variable with one-character
991 name e.
992 \V(ev The contents of the environment variable with two-character name
993 ev.
994 \V[env]
995 The contents of the environment variable with arbitrarily long
996 name env.
997 \w’string’
998 The width of the glyph sequence string.
999 \x’N’ Extra line-space function (negative before, positive after).
1000 \X’string’
1001 Output string as device control function.
1002 \Yn Output string variable or macro with one-character name n unin‐
1003 terpreted as device control function.
1004 \Y(nm Output string variable or macro with two-character name nm unin‐
1005 terpreted as device control function.
1006 \Y[name]
1007 Output string variable or macro with arbitrarily long name name
1008 uninterpreted as device control function.
1009 \zc Print c with zero width (without spacing).
1010 \Z’anything’
1011 Print anything and then restore the horizontal and vertical
1012 position; anything may not contain tabs or leaders.
1013 The escape sequences \e, \., \", \$, \*, \a, \n, \t, \g, and \newline
1015 are interpreted in copy mode.
1016 Escape sequences starting with \( or \[ do not represent single charac‐
1018 ter escape sequences, but introduce escape names with two or more char‐
1019 acters.
1020 If a backslash is followed by a character that does not constitute a
1022 defined escape sequence, the backslash is silently ignored and the
1023 character maps to itself.
1024 Special Characters
1026 [Note: ‘Special Characters’ is a misnomer; those entities are (output)
1027 glyphs, not (input) characters.]
1028 Common special characters are predefined by escape sequences of the
1030 form \(xy with characters x and y. In groff, it is also possible to
1031 use the writing \[xy] as well.
1032 Some of these special characters exist in the usual font while most of
1034 them are only available in the special font. Below you can see a small
1035 selection of the most important glyphs; a complete list can be found in
1036 groff_char(7).
1037 \(Do Dollar $
1039 \(Eu Euro €
1040 \(Po British pound sterling £
1041 \(aq Apostrophe quote '
1042 \(bu Bullet sign ·
1043 \(co Copyright ©
1044 \(cq Single closing quote (right) ’
1045 \(ct Cent ¢
1046 \(dd Double dagger ‡
1047 \(de Degree °
1048 \(dg Dagger †
1049 \(dq Double quote (ASCII 34) "
1050 \(em Em-dash —
1051 \(en En-dash –
1052 \(hy Hyphen ‐
1053 \(lq Double quote left “
1054 \(oq Single opening quote (left) ‘
1055 \(rg Registered sign ®
1056 \(rq Double quote right ”
1057 \(rs Printable backslash character \
1058 \(sc Section sign §
1059 \(tm Trademark symbol ™
1060 \(ul Underline character _
1061 \(== Identical ≡
1062 \(>= Larger or equal ≥
1063 \(<= Less or equal ≤
1064 \(!= Not equal ≠
1065 \(-> Right arrow →
1066 \(<- Left arrow ←
1067 \(+- Plus-minus sign ±
1068 Unicode Characters
1070 There is the extended escape u that allows to include all available
1071 Unicode characters into some roff file.
1072 \[uxxxx]
1074 u is the escape name. xxxx is a hexadecimal number of 4 hex
1075 digits, such as 0041 for the letter A, see \[u0041].
1076 \[uyyyyy]
1078 u is the escape name. yyyyy is a hexadecimal number of 5 hex
1079 digits, such as 2FA1A for a Chinese looking character for CJK
1080 Compatibility Ideographs Supplement, see \[u2FA1A].
1081 Both hexadecimal collections mean the corresponding Unicode code for a
1083 character.
1084 \[uhex1_hex2]
1086 \[uhex1_hex2_hex3]
1087 hex1, hex2, and hex3 are all Unicode hexadecimal codes (4 or 5
1088 hex digits) that are used for overstriking, e.g. \[u0041_0301]
1089 is A acute Á.
1090 The availability of the Unicode characters depends on the used font.
1092 For text mode, the device -Tutf8 is quite complete, for troff modes it
1093 might happen that some or many characters will not be displayed.
1094 Please check your fonts.
1095 Strings
1097 Strings are defined by the ds request and can be retrieved by the \*
1098 escape sequence.
1099 Strings share their name space with macros. So strings and macros
1101 without arguments are roughly equivalent; it is possible to call a
1102 string like a macro and vice-versa, but this often leads to unpre‐
1103 dictable results. The following string is the only one predefined in
1104 groff.
1105 \*[.T] The name of the current output device as specified by the -T
1107 command line option.
1108
1110 Registers are variables that store a value. In groff, most registers
1111 store numerical values (see section NUMERICAL EXPRESSIONS above), but
1112 some can also hold a string value.
1113 Each register is given a name. Arbitrary registers can be defined and
1115 set with the nr request.
1116 The value stored in a register can be retrieved by the escape sequences
1118 introduced by \n.
1119 Most useful are predefined registers. In the following the notation
1121 name is used to refer to register name to make clear that we speak
1122 about registers. Please keep in mind that the \n[] decoration is not
1123 part of the register name.
1124 Read-only Registers
1126 The following registers have predefined values that should not be modi‐
1127 fied by the user (usually, registers starting with a dot are read-
1128 only). Mostly, they provide information on the current settings or
1129 store results from request calls.
1130 \n[$$] The process ID of troff.
1132 \n[.$] Number of arguments in the current macro or string.
1133 \n[.a] Post-line extra line-space most recently utilized using \x.
1134 \n[.A] Set to 1 in troff if option -A is used; always 1 in nroff.
1135 \n[.b] The emboldening offset while .bd is active.
1136 \n[.br] Within a macro, set to 1 if macro called with the ‘normal’
1137 control character, and to 0 otherwise.
1138 \n[.c] Current input line number.
1139 \n[.C] 1 if compatibility mode is in effect, 0 otherwise.
1140 \n[.cdp] The depth of the last glyph added to the current environment.
1141 It is positive if the glyph extends below the baseline.
1142 \n[.ce] The number of lines remaining to be centered, as set by the
1143 ce request.
1144 \n[.cht] The height of the last glyph added to the current environ‐
1145 ment. It is positive if the glyph extends above the base‐
1146 line.
1147 \n[.color]
1148 1 if colors are enabled, 0 otherwise.
1149 \n[.csk] The skew of the last glyph added to the current environment.
1150 The skew of a glyph is how far to the right of the center of
1151 a glyph the center of an accent over that glyph should be
1152 placed.
1153 \n[.d] Current vertical place in current diversion; equal to regis‐
1154 ter nl.
1155 \n[.ev] The name or number of the current environment (string-val‐
1156 ued).
1157 \n[.f] Current font number.
1158 \n[.F] The name of the current input file (string-valued).
1159 \n[.fam] The current font family (string-valued).
1160 \n[.fn] The current (internal) real font name (string-valued).
1161 \n[.fp] The number of the next free font position.
1162 \n[.g] Always 1 in GNU troff. Macros should use it to test if run‐
1163 ning under groff.
1164 \n[.h] Text base-line high-water mark on current page or diversion.
1165 \n[.H] Available horizontal resolution in basic units.
1166 \n[.height]
1167 The current font height as set with \H.
1168 \n[.hla] The current hyphenation language as set by the hla request.
1169 \n[.hlc] The number of immediately preceding consecutive hyphenated
1170 lines.
1171 \n[.hlm] The maximum allowed number of consecutive hyphenated lines,
1172 as set by the hlm request.
1173 \n[.hy] The current hyphenation flags (as set by the hy request).
1174 \n[.hym] The current hyphenation margin (as set by the hym request).
1175 \n[.hys] The current hyphenation space (as set by the hys request).
1176 \n[.i] Current indentation.
1177 \n[.in] The indentation that applies to the current output line.
1178 \n[.int] Positive if last output line contains \c.
1179 \n[.j] The current adjustment mode. It can be stored and used to
1180 set adjustment. (n = 1, b = 1, l = 0, r = 5, c = 3).
1181 \n[.k] The current horizontal output position (relative to the cur‐
1182 rent indentation).
1183 \n[.kern] 1 if pairwise kerning is enabled, 0 otherwise.
1184 \n[.l] Current line length.
1185 \n[.L] The current line spacing setting as set by .ls.
1186 \n[.lg] The current ligature mode (as set by the lg request).
1187 \n[.linetabs]
1188 The current line-tabs mode (as set by the linetabs request).
1189 \n[.ll] The line length that applies to the current output line.
1190 \n[.lt] The title length (as set by the lt request).
1191 \n[.m] The current drawing color (string-valued).
1192 \n[.M] The current background color (string-valued).
1193 \n[.n] Length of text portion on previous output line.
1194 \n[.ne] The amount of space that was needed in the last ne request
1195 that caused a trap to be sprung. Useful in conjunction with
1196 register .trunc.
1197 \n[.ns] 1 if in no-space mode, 0 otherwise.
1198 \n[.o] Current page offset.
1199 \n[.O] The suppression nesting level (see \O).
1200 \n[.p] Current page length.
1201 \n[.P] 1 if the current page is being printed, 0 otherwise (as
1202 determined by the -o command line option).
1203 \n[.pe] 1 during page ejection, 0 otherwise.
1204 \n[.pn] The number of the next page: either the value set by a pn
1205 request, or the number of the current page plus 1.
1206 \n[.ps] The current point size in scaled points.
1207 \n[.psr] The last-requested point size in scaled points.
1208 \n[.pvs] The current post-vertical line spacing.
1209 \n[.R] The number of unused number registers. Always 10000 in GNU
1210 troff.
1211 \n[.rj] The number of lines to be right-justified as set by the rj
1212 request.
1213 \n[.s] Current point size as a decimal fraction.
1214 \n[.slant]
1215 The slant of the current font as set with \S.
1216 \n[.sr] The last requested point size in points as a decimal fraction
1217 (string-valued).
1218 \n[.ss] The value of the parameters set by the first argument of the
1219 ss request.
1220 \n[.sss] The value of the parameters set by the second argument of the
1221 ss request.
1222 \n[.sty] The current font style (string-valued).
1223 \n[.t] Vertical distance to the next trap.
1224 \n[.T] Set to 1 if option -T is used.
1225 \n[.tabs] A string representation of the current tab settings suitable
1226 for use as an argument to the ta request.
1227 \n[.trunc]
1228 The amount of vertical space truncated by the most recently
1229 sprung vertical position trap, or, if the trap was sprung by
1230 a ne request, minus the amount of vertical motion produced by
1231 .ne. Useful in conjunction with the register .ne.
1232 \n[.u] Equal to 1 in fill mode and 0 in no-fill mode.
1233 \n[.U] Equal to 1 in safer mode and 0 in unsafe mode.
1234 \n[.v] Current vertical line spacing.
1235 \n[.V] Available vertical resolution in basic units.
1236 \n[.vpt] 1 if vertical position traps are enabled, 0 otherwise.
1237 \n[.w] Width of previous glyph.
1238 \n[.warn] The sum of the number codes of the currently enabled warn‐
1239 ings.
1240 \n[.x] The major version number.
1241 \n[.y] The minor version number.
1242 \n[.Y] The revision number of groff.
1243 \n[.z] Name of current diversion.
1244 \n[.zoom] Zoom factor for current font (in multiples of 1/1000th; zero
1245 if no magnification).
1246 Writable Registers
1248 The following registers can be read and written by the user. They have
1249 predefined default values, but these can be modified for customizing a
1250 document.
1251 \n[%] Current page number.
1253 \n[c.] Current input line number.
1254 \n[ct] Character type (set by width function \w).
1255 \n[dl] Maximal width of last completed diversion.
1256 \n[dn] Height of last completed diversion.
1257 \n[dw] Current day of week (1–7).
1258 \n[dy] Current day of month (1–31).
1259 \n[hours] The number of hours past midnight. Initialized at start-up.
1260 \n[hp] Current horizontal position at input line.
1261 \n[llx] Lower left x-coordinate (in PostScript units) of a given
1262 PostScript image (set by .psbb).
1263 \n[lly] Lower left y-coordinate (in PostScript units) of a given
1264 PostScript image (set by .psbb).
1265 \n[ln] Output line number.
1266 \n[lsn] The number of leading spaces of an input line.
1267 \n[lss] The horizontal space corresponding to the leading spaces of
1268 an input line.
1269 \n[minutes]
1270 The number of minutes after the hour. Initialized at start-
1271 up.
1272 \n[mo] Current month (1–12).
1273 \n[nl] Vertical position of last printed text base-line.
1274 \n[opmaxx]
1275 \n[opmaxy]
1276 \n[opminx]
1277 \n[opminy]
1278 These four registers mark the top left and bottom right hand
1279 corners of a box which encompasses all written glyphs. They
1280 are reset to -1 by \O0 or \O1.
1281 \n[rsb] Like register sb, but takes account of the heights and depths
1282 of glyphs.
1283 \n[rst] Like register st, but takes account of the heights and depths
1284 of glyphs.
1285 \n[sb] Depth of string below base line (generated by width function
1286 \w).
1287 \n[seconds]
1288 The number of seconds after the minute. Initialized at
1289 start-up.
1290 \n[skw] Right skip width from the center of the last glyph in the \w
1291 argument.
1292 \n[slimit]
1293 If greater than 0, the maximum number of objects on the input
1294 stack. If ≤0 there is no limit, i.e., recursion can continue
1295 until virtual memory is exhausted.
1296 \n[ssc] The amount of horizontal space (possibly negative) that
1297 should be added to the last glyph before a subscript (gener‐
1298 ated by width function \w).
1299 \n[st] Height of string above base line (generated by width function
1300 \w).
1301 \n[systat]
1302 The return value of the system() function executed by the
1303 last sy request.
1304 \n[urx] Upper right x-coordinate (in PostScript units) of a given
1305 PostScript image (set by .psbb).
1306 \n[ury] Upper right y-coordinate (in PostScript units) of a given
1307 PostScript image (set by .psbb).
1308 \n[year] The current year (year 2000 compliant).
1309 \n[yr] Current year minus 1900. For Y2K compliance use register
1310 year instead.
1311
1313 In the RUNOFF language, the underlining was quite easy. But in roff
1314 this is much more difficult.
1315 Underlining with .ul
1317 There exists a groff request .ul (see above) that can underline the
1318 next or further source lines in nroff, but in troff it produces only a
1319 font change into italic. So this request is not really useful.
1320 Underlining with .UL from ms
1322 In the ‘ms’ macro package in tmac/s.tmac groff_ms(7), there is the
1323 macro .UL. But this works only in troff, not in nroff.
1324 Underlining macro definitions
1326 So one can use the italic nroff idea from .ul and the troff definition
1327 in ms for writing a useful new macro, something like
1328 .de UNDERLINE
1329 . ie n \\$1\f[I]\\$2\f[P]\\$3
1330 . el \\$1\Z'\\$2'\v'.25m'\D'l \w'\\$2'u 0'\v'-.25m'\[rs]\$3
1331 ..
1332 If doclifter (1) makes trouble, change the macro name UNDERLINE into
1333 some 2-letter word, like Ul. Moreover change the font writing from
1334 \f[P] to \fP.
1335 Underlining without macro definitions
1337 If one does not want to use macro definitions, e.g. when doclifter gets
1338 lost, use the following:
1339 .ds u1 before
1340 .ds u2 in
1341 .ds u3 after
1342 .ie n \*[u1]\f[I]\*[u2]\f[P]\*[u3]
1343 .el \*[u1]\Z'\*[u2]'\v'.25m'\D'l \w'\*[u2]'u 0'\v'-.25m'\*[u3]
1344 Due to doclifter, it might be necessary to change the variable writing
1345 \[xy] and \*[xy] into the strange ancient writing \*(xy and \(xy, and
1346 so on.
1347 Then these lines could look like
1349 .ds u1 before
1350 .ds u2 in
1351 .ds u3 after
1352 .ie n \*[u1]\fI\*(u2\fP\*(u3
1353 .el \*(u1\Z'\*(u2'\v'.25m'\D'l \w'\*(u2'u 0'\v'-.25m'\*(u3
1354 The result looks like
1356 before _i_n after
1357 Underlining with Overstriking \z and \(ul
1359 There is another possibility for underlining by using overstriking with
1360 \zc (print c with zero width without spacing) and \(ul (underline char‐
1361 acter). This produces the underlining of 1 character, both in nroff
1362 and in troff.
1363 For example the underlining of a character say t looks like \z\[ul]t or
1365 \z\(ult
1366 Longer words look then a bit strange, but a useful mode is to write
1368 each character into a whole own line. To underlines the 3 character
1369 part "tar" of the word "start":
1370 before s\
1371 \z\[ul]t\
1372 \z\[ul]a\
1373 \z\[ul]r\
1374 t after
1375 or
1376 before s\
1377 \z\(ult\
1378 \z\(ula\
1379 \z\(ulr\
1380 t after
1381 The result looks like
1383 before s_t_a_rt after
1384
1386 The differences of the groff language in comparison to classical troff
1387 as defined by [CSTR #54] are documented in groff_diff(7).
1388 The groff system provides a compatibility mode, see groff(1) on how to
1390 invoke this.
1391
1393 Report bugs to the groff bug mailing list ⟨bug-groff@gnu.org⟩. Include
1394 a complete, self-contained example that will allow the bug to be repro‐
1395 duced, and say which version of groff you are using.
1396
1398 The main source of information for the groff language is the groff
1399 info(1) file. Besides the gory details, it contains many examples.
1400 groff(1)
1402 the usage of the groff program and pointers to the documentation
1403 and availability of the groff system.
1404 groff_diff(7)
1406 the differences of the groff language as compared to classical
1407 roff. This is the authoritative document for the predefined
1408 language elements that are specific to groff.
1409 groff_char(7)
1411 the predefined groff special characters (glyphs).
1412 groff_font(5)
1414 the specification of fonts and the DESC file.
1415 roff(7)
1417 the history of roff, the common parts shared by all roff sys‐
1418 tems, and pointers to further documentation.
1419 [CSTR #54]
1421 Nroff/Troff User's Manual by Ossanna & Kernighan ⟨http://
1422 cm.bell-labs.com/cm/cs/cstr/54.ps.gz⟩ — the bible for classical
1423 troff.
1424
1426 This file is part of groff, the GNU roff type-setting system.
1427 Copyright © 2000-2014 Free Software Foundation, Inc.
1429 Permission is granted to copy, distribute and/or modify this document
1431 under the terms of the GNU Free Documentation License, Version 1.3 or
1432 any later version published by the Free Software Foundation; with no
1433 Front-Cover Texts, and with no Back-Cover Texts.
1434 A copy of the Free Documentation License is included as a file called
1436 FDL in the main directory of the groff source package. It is also
1437 available in the internet at ⟨http://www.gnu.org/copyleft/fdl.html⟩.
1438
1440 This documentation was written by Bernd Warken ⟨groff-
1441 bernd.warken-72@web.de⟩ and is appended and maintained by Werner
1442 Lemberg ⟨wl@gnu.org⟩.
1443Groff Version 1.22.3 4 November 2014 GROFF(7)