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GROFF(7) Miscellaneous Information Manual GROFF(7) NAME groff - a short reference for the GNU roff language DESCRIPTION The name groff stands for GNU roff and is the free implementation of the roff type-setting system. See roff(7) for a survey and the background of the groff system. This document gives only short descriptions of the predefined roff language elements as used in groff. Both the classical features and the groff ex- tensions are provided. Historically, the roff language was called troff. groff is compatible with the classical system and provides proper extensions. So in GNU, the terms roff, troff, and groff language could be used as synonyms. However troff slightly tends to refer more to the classical aspects, whereas groff empha- sizes the GNU extensions, and roff is the general term for the language. This file is only a short version of the complete documentation that is found in the groff info(1) file, which contains more detailed, actual, and concise information. The general syntax for writing groff documents is relatively easy, but writing extensions to the roff language can be a bit harder. The roff language is line-oriented. There are only two kinds of lines, control lines and text lines. The control lines start with a control char- acter, by default a period "." or a single quote "'"; all other lines are text lines. Control lines represent commands, optionally with arguments. They have the following syntax. The leading control character can be followed by a com- mand name; arguments, if any, are separated by blanks from the command name and among themselves, for example, .command_name arg1 arg2 For indentation, any number of space or tab characters can be inserted be- tween the leading control character and the command name, but the control character must be on the first position of the line. Text lines represent the parts that will be printed. They can be modified by escape sequences, which are recognized by a leading backslash `\'. These are in-line or even in-word formatting elements or functions. Some of these take arguments separated by single quotes "'", others are regu- lated by a length encoding introduced by an open parenthesis `(' or en- closed in brackets `[' and `]'. The roff language provides flexible instruments for writing language exten- sion, such as macros. When interpreting macro definitions, the roff system enters a special operating mode, called the copy mode. The copy mode behavior can be quite tricky, but there are some rules that ensure a safe usage. 1. Printable backslashes must be denoted as \e. To be more precise, \e represents the current escape character. To get a backslash glyph, use \(rs or \[rs]. 2. Double all backslashes. 3. Begin all text lines with the special non-spacing character \&. This does not produce the most efficient code, but it should work as a first measure. For better strategies, see the groff info file and groff_tmac(5). Reading roff source files is easier, just reduce all double backslashes to a single one in all macro definitions. GROFF ELEMENTS The roff language elements add formatting information to a text file. The fundamental elements are predefined commands and variables that make roff a full-blown programming language. There are two kinds of roff commands, possibly with arguments. Requests are written on a line of their own starting with a dot `.' or a "'", whereas Escape sequences are in-line functions and in-word formatting ele- ments starting with a backslash `\'. The user can define her own formatting commands using the de request. These commands are called macros, but they are used exactly like requests. Macro packages are pre-defined sets of macros written in the groff lan- guage. A user's possibilities to create escape sequences herself is very limited, only special characters can be mapped. The groff language provides several kinds of variables with different in- terfaces. There are pre-defined variables, but the user can define her own variables as well. String variables store character sequences. They are set with the ds re- quest and retrieved by the \* escape sequences. Strings can have vari- ables. Register variables can store numerical values, numbers with a scale unit, and occasionally string-like objects. They are set with the nr request and retrieved by the \n escape sequences. Environments allow the user to temporarily store global formatting parame- ters like line length, font size, etc. for later reuse. This is done by the ev request. Fonts are identified either by a name or by an internal number. The cur- rent font is chosen by the ft request or by the \f escape sequences. Each device has special fonts, but the following fonts are available for all de- vices. R is the standard font Roman. B is its bold counterpart. The italic font is called I and is available everywhere, but on text devices it is displayed as an underlined Roman font. For the graphical output de- vices, there exist constant-width pendants of these fonts, CR, CI, and CB. On text devices, all characters have a constant width anyway. Moreover, there are some advanced roff elements. A diversion stores infor- mation into a macro for later usage. A trap is a positional condition like a certain number of lines from page top or in a diversion or in the input. Some action can be prescribed to be run automatically when the condition is met. More detailed information and examples can be found in the groff info file. CONTROL CHARACTERS There is a small set of characters that have a special controlling task in certain conditions. . A dot is only special at the beginning of a line or after the condi- tion in the requests if, ie, el, and while. There it is the control character that introduces a request (or macro). The special behav- ior can be delayed by using the \. escape. By using the cc re- quest, the control character can be set to a different character, making the dot `.' a non-special character. In all other positions, it just means a dot character. In text paragraphs, it is advantageous to start each sentence at a line of its own. ' The single quote has two controlling tasks. At the beginning of a line and in the conditional requests it is the non-breaking control character. That means that it introduces a request like the dot, but with the additional property that this request doesn't cause a linebreak. By using the c2 request, the non-break control character can be set to a different character. As a second task, it is the most commonly used argument separator in some functional escape sequences (but any pair of characters not part of the argument will work). In all other positions, it denotes the single quote or apostrophe character. Groff provides a print- able representation with the \(cq escape sequence. " The double quote is used to enclose arguments in requests, macros, and strings. In the ds and as requests, a leading double quote in the argument will be stripped off, making everything else afterwards the string to be defined (enabling leading whitespace). The escaped double quote \" introduces a comment. Otherwise, it is not special. Groff provides a printable representation with the \(dq escape se- quence. \ The backslash usually introduces an escape sequence (this can be changed with the ec request). A printed version of the escape char- acter is the \e escape; a backslash glyph can be obtained by \(rs. ( The open parenthesis is only special in escape sequences when intro- ducing an escape name or argument consisting of exactly two charac- ters. In groff, this behavior can be replaced by the [] construct. [ The opening bracket is only special in groff escape sequences; there it is used to introduce a long escape name or long escape argument. Otherwise, it is non-special, e.g. in macro calls. ] The closing bracket is only special in groff escape sequences; there it terminates a long escape name or long escape argument. Other- wise, it is non-special. space Space characters are only functional characters. They separate the arguments in requests, macros, and strings, and the words in text lines. They are subject to groff's horizontal spacing calculations. To get a defined space width, escape sequences like `\ ' (this is the escape character followed by a space), \|, \^, or \h should be used. newlineIn text paragraphs, newlines mostly behave like space characters. Continuation lines can be specified by an escaped newline, i.e., by specifying a backslash `\' as the last character of a line. tab If a tab character occurs during text the interpreter makes a hori- zontal jump to the next pre-defined tab position. There is a so- phisticated interface for handling tab positions. NUMERICAL EXPRESSIONS A numerical value is a signed or unsigned integer or float with or without an appended scaling indicator. A scaling indicator is a one-character ab- breviation for a unit of measurement. A number followed by a scaling indi- cator signifies a size value. By default, numerical values do not have a scaling indicator, i.e., they are normal numbers. The roff language defines the following scaling indicators. c Centimeter i Inch P Pica = 1/6 inch p Point = 1/72 inch m Em = the font size in points (width of letter `m') M 100th of an Em n En = Em/2 u Basic unit for actual output device v Vertical line space in basic units scaled point = 1/sizescale of a point (defined in font DESC file) f Scale by 65536. Numerical expressions are combinations of the numerical values defined above with the following arithmetical operators already defined in classi- cal troff. + Addition - Subtraction * Multiplication / Division % Modulo = Equals == Equals < Less than > Greater than <= Less or equal >= Greater or equal & Logical and : Logical or ! Logical not ( Grouping of expressions ) Close current grouping Moreover, groff added the following operators for numerical expressions: e1>?e2 The maximum of e1 and e2. e1<?e2 The minimum of e1 and e2. (c;e) Evaluate e using c as the default scaling indicator. For details see the groff info file. CONDITIONS Conditions occur in tests raised by the if, ie, and the while requests. The following table characterizes the different types of conditions. N A numerical expression N yields true if its value is greater than 0. !N True if the value of I is 0. 's1's2' True if string s1 is identical to string s2. !'s1's2' True if string s1 is not identical to string s2. cch True if there is a character ch available. dname True if there is a string, macro, diversion, or request called name. e Current page number is even. o Current page number is odd. mname True if there is a color called name. n Formatter is nroff. rreg True if there is a register named reg. t Formatter is troff. REQUESTS This section provides a short reference for the predefined requests. In groff, request and macro names can be arbitrarily long. No bracketing or marking of long names is needed. Most requests take one or more arguments. The arguments are separated by space characters (no tabs!); there is no inherent limit for their length or number. An argument can be enclosed by a pair of double quotes. This is very handy if an argument contains space characters, e.g., "arg with space" denotes a single argument. Some requests have optional arguments with a different behaviour. Not all of these details are outlined here. Refer to the groff info file and groff_diff(7) for all details. In the following request specifications, most argument names were chosen to be descriptive. Only the following denotations need clarification. c denotes a single character. font a font either specified as a font name or a font number. anything all characters up to the end of the line or within \{ and \}. n is a numerical expression that evaluates to an integer value. N is an arbitrary numerical expression, signed or unsigned. +/-N has three meanings depending on its sign, described below. If an expression defined as +/-N starts with a `+' sign the resulting value of the expression will be added to an already existing value inherent to the related request, e.g. adding to a number register. If the expression starts with a `-' the value of the expression will be subtracted from the request value. Without a sign, N replaces the existing value directly. To assign a nega- tive number either prepend 0 or enclose the negative number in parentheses. Request Short Reference . Empty line, ignored. Useful for structuring documents. .\" anything Complete line is a comment. .ab string Print string on standard error, exit program. .ad Begin line adjustment for output lines in current adjust mode. .ad c Start line adjustment in mode c (c=l,r,b,n). .af register c Assign format c to register (c=l,i,I,a,A). .aln alias register Create alias name for register. .als alias object Create alias name for request, string, macro, or diversion ob- ject. .am macro Append to macro until .. is encountered. .am macro end Append to macro until .end is called. .ami macro Append to a macro whose name is contained in the string register macro until .. is encountered. .ami macro end Append to a macro indirectly. macro and end are string registers whose contents are interpolated for the macro name and the end macro, respectively. .am1 macro Same as .am but with compatibility mode switched off during macro expansion. .am1 macro end Same as .am but with compatibility mode switched off during macro expansion. .as stringvar anything Append anything to stringvar. .asciify diversion Unformat ASCII characters, spaces, and some escape sequences in diversion. .as1 stringvar anything Same as .as but with compatibility mode switched off during string expansion. .backtrace Print a backtrace of the input on stderr. .bd font N Embolden font by N-1 units. .bd S font N Embolden Special Font S when current font is font. .blm Unset the blank line macro. .blm macro Set the blank line macro to macro. .box End current diversion. .box macro Divert to macro, omitting a partially filled line. .boxa End current diversion. .boxa macro Divert and append to macro, omitting a partially filled line. .bp Eject current page and begin new page. .bp +/-N Eject current page; next page number +/-N. .br Line break. .brp Break and spread output line. Same as \p. .break Break out of a while loop. .c2 Reset no-break control character to "'". .c2 c Set no-break control character to c. .cc Reset control character to `.'. .cc c Set control character to c. .ce Center the next input line. .ce N Center following N input lines. .cf filename Copy contents of file filename unprocessed to stdout or to the diversion. .cflags mode c1 c2 ... Treat characters c1, c2, ... according to mode number. .ch trap N Change trap location to N . .char c anything Define character c as string anything. .chop object Chop the last character off macro, string, or diversion object. .close stream Close the stream. .color Enable colors. .color N If N is zero disable colors, otherwise enable them. .continue Finish the current iteration of a while loop. .cp Enable compatibility mode. .cp N If N is zero disable compatibility mode, otherwise enable it. .cs font N M Set constant character width mode for font to N/36 ems with em M. .cu N Continuous underline in nroff, like .ul in troff. .da End current diversion. .da macro Divert and append to macro. .de macro Define or redefine macro until .. is encountered. .de macro end Define or redefine macro until .end is called. .de1 macro Same as .de but with compatibility mode switched off during macro expansion. .de1 macro end Same as .de but with compatibility mode switched off during macro expansion. .defcolor color scheme component Define or redefine a color with name color. scheme can be rgb, cym, cymk, gray, or grey. component can be single components specified as fractions in the range 0 to 1 (default scaling indi- cator f), as a string of two-digit hexadecimal color components with a leading #, or as a string of four-digit hexadecimal compo- nents with two leading #. The color default can't be redefined. .dei macro Define or redefine a macro whose name is contained in the string register macro until .. is encountered. .dei macro end Define or redefine a macro indirectly. macro and end are string registers whose contents are interpolated for the macro name and the end macro, respectively. .di End current diversion. .di macro Divert to macro . .do name Interpret .name with compatibility mode disabled. .ds stringvar anything Set stringvar to anything. .ds1 stringvar anything Same as .ds but with compatibility mode switched off during string expansion. .dt N trap Set diversion trap to position N (default scaling indicator v). .ec Reset escape character to `\'. .ec c Set escape character to c. .ecr Restore escape character saved with .ecs. .ecs Save current escape character. .el anything Else part for if-else (ie) request. .em macro The macro will be run after the end of input. .eo Turn off escape character mechanism. .ev Switch to previous environment. .ev env Push down environment number or name env and switch to it. .evc env Copy the contents of environment env to the current environment. No pushing or popping. .ex Exit from roff processing. .fam Return to previous font family. .fam name Set the current font family to name. .fc Disable field mechanism. .fc a Set field delimiter to a and pad character to space. .fc a b Set field delimiter to a and pad character to b. .fchar c anything Define fallback character c as string anything. .fi Fill output lines. .fl Flush output buffer. .fp n font Mount font on position n. .fp n internal external Mount font with long external name to short internal name on po- sition n. .fspecial font s1 s2 ... When the current font is font, then the fonts s1, s2, ... will be special. .ft Return to previous font. Same as \f[] or \fP. .ft font Change to font name or number font; same as \f[font] escape se- quence. .ftr font1 font2 Translate font1 to font2. .hc Remove additional hyphenation indicator character. .hc c Set up additional hyphenation indicator character c. .hcode c1 code1 c2 code2 ... Set the hyphenation code of character c1 to code1, that of c2 to code2, etc. .hla lang Set the current hyphenation language to lang. .hlm n Set the maximum number of consecutive hyphenated lines to n. .hpf file Read hyphenation patterns from file. .hpfa file Append hyphenation patterns from file. .hpfcode file Set input mapping for .hpf. .hw words List of words with exceptional hyphenation. .hy N Switch to hyphenation mode N. .hym n Set the hyphenation margin to n (default scaling indicator m). .hys n Set the hyphenation space to n. .ie cond anything If cond then anything else goto .el. .if cond anything If cond then anything; otherwise do nothing. .ig Ignore text until .. is encountered. .ig end Ignore text until .end. .in Change to previous indent value. .in +/-N Change indent according to +/-N (default scaling indicator m). .it N trap Set an input-line count trap for the next N lines. .itc N trap Same as .it but count lines interrupted with \c as one line. .kern Enable pairwise kerning. .kern n If n is zero, disable pairwise kerning, otherwise enable it. .lc Remove leader repetition character. .lc c Set leader repetition character to c. .length register anything Write the length of the string anything in register. .linetabs Enable line-tabs mode (i.e., calculate tab positions relative to output line). .linetabs n If n is zero, disable line-tabs mode, otherwise enable it. .lf N file Set input line number to N and filename to file. .lg N Ligature mode on if N>0. .ll Change to previous line length. .ll +/-N Set line length according to +/-N (default size 6.5i, default scaling indicator m). .ls Change to the previous value of additional intra-line skip. .ls N Set additional intra-line skip value to N, i.e., N-1 blank lines are inserted after each text output line. .lt +/-N Length of title (default scaling indicator m). .mc Margin character off. .mc c Print character c after each text line at actual distance from right margin. .mc c N Set margin character to c and distance to N from right margin (default scaling indicator m). .mk register Mark current vertical position in register. .mso file The same as the .so request except that file is searched in the tmac directories. .na No output-line adjusting. .ne Need a one-line vertical space. .ne N Need N vertical space (default scaling indicator v). .nf No filling or adjusting of output-lines. .nh No hyphenation. .nm Number mode off. .nm +/-N [M [S [I]]] In line number mode, set number, multiple, spacing, and indent. .nn Do not number next line. .nn N Do not number next N lines. .nop anything Always execute anything. .nr register +/-N M Define or modify register using +/-N with auto-increment M. .nroff Make the built-in condition n true and t false. .ns Turn no-space mode on. .nx Immediately jump to end of current file. .nx filename Next file. .open stream filename Open register filename for writing and associate the stream named register stream with it. .opena stream filename Like .open but append to it. .os Output vertical distance that was saved by the sv request. .output string Emit string directly to intermediate output, allowing leading whitespace if string starts with " (which will be stripped off). .pc Reset page number character to `%'. .pc c Page number character. .pi program Pipe output to program (nroff only). .pl Set page length to default 11i. The current page length is stored in register .p. .pl +/-N Change page length to +/-N (default scaling indicator v). .pm Print macro names and sizes (number of blocks of 128 bytes). .pm t Print only total of sizes of macros (number of 128 bytes blocks). .pn +/-N Next page number N. .pnr Print the names and contents of all currently defined number reg- isters on stderr. .po Change to previous page offset. The current page offset is available in register .o. .po +/-N Page offset N. .ps Return to previous point-size. .ps +/-N Point size; same as \s[+/-N]. .psbb filename Get the bounding box of a PostScript image filename. .pso command This behaves like the so request except that input comes from the standard output of command. .ptr Print the names and positions of all traps (not including input line traps and diversion traps) on stderr. .pvs Change to previous post-vertical line spacing. .pvs +/-N Change post-vertical line spacing according to +/-N (default scaling indicator p). .rchar c1 c2 ... Remove the definitions of characters c1, c2, ... .rd prompt Read insertion. .return Return from a macro. .rj n Right justify the next n input lines. .rm name Remove request, macro, or string name. .rn old new Rename request, macro, or string old to new. .rnn reg1 reg2 Rename register reg1 to reg2. .rr register Remove register. .rs Restore spacing; turn no-space mode off. .rt +/-N Return (upward only) to marked vertical place (default scaling indicator v). .shc Reset soft hyphen character to \(hy. .shc c Set the soft hyphen character to c. .shift n In a macro, shift the arguments by n positions. .sizes s1 s2 ... sn [0] Set available font sizes similar to the sizes command in a DESC file. .so filename Include source file. .sp Skip one line vertically. .sp N Space vertical distance N up or down according to sign of N (de- fault scaling indicator v). .special s1 s2 ... Fonts s1, s2, etc. are special and will be searched for charac- ters not in the current font. .spreadwarn Toggle the spread warning on and off without changing its value. .spreadwarn limit Emit a warning if each space in an output line is widened by limit or more (default scaling indicator m). .ss N Space-character size set to N/12 of the spacewidth in the current font. .ss N M Space-character size set to N/12 and sentence space size set to M/12 of the spacewidth in the current font (=1/3 em). .sty n style Associate style with font position n. .substring xx n1 n2 Replace the string named xx with the substring defined by the in- dices n1 and n2. .sv Save 1v of vertical space. .sv N Save the vertical distance N for later output with os request. .sy command-line Execute program command-line. .ta T N Set tabs after every position that is a multiple of N (default scaling indicator m). .ta n1 n2 ... nn T r1 r2 ... rn Set tabs at positions n1, n2, ..., nn, then set tabs at nn+r1, nn+r2, ..., nn+rn, then at nn+rn+r1, nn+rn+r2, ..., nn+rn+rn, and so on. .tc Remove tab repition character. .tc c Set tab repetition character to c. .ti +/-N Temporary indent next line (default scaling indicator m). .tkf font s1 n1 s2 n2 Enable track kerning for font. .tl 'left'center'right' Three-part title. .tm anything Print anything on terminal (UNIX standard message output). .tm1 anything Print anything on terminal (UNIX standard message output), allow- ing leading whitespace if anything starts with " (which will be stripped off). .tmc anything Similar to .tm1 without emitting a final newline. .tr abcd... Translate a to b, c to d, etc. on output. .trf filename Transparently output the contents of file filename. .trin abcd... This is the same as the tr request except that the asciify re- quest will use the character code (if any) before the character translation. .trnt abcd... This is the same as the tr request except that the translations do not apply to text that is transparently throughput into a di- version with \!. .troff Make the built-in condition t true and n false. .uf font Underline font set to font (to be switched to by .ul). .ul N Underline (italicize in troff) N input lines. .unformat diversion Unformat space characters and tabs, preserving font information in diversion. .vpt n Enable vertical position traps if n is non-zero, disable them otherwise. .vs Change to previous vertical base line spacing. .vs +/-N Set vertical base line spacing according to +/-N (default scaling indicator p). Default value is 12p. .warn n Set warnings code to n. .warnscale si Set scaling indicator used in warnings to si. .wh N Remove (first) trap at position N. .wh N trap Set location trap; negative means from page bottom. .while cond anything While condition cond is true, accept anything as input. .write stream anything Write anything to the stream named stream. .writec stream anything Similar to .write without emitting a final newline. .writem stream xx Write contents of macro or string xx to the stream named stream. Besides these standard groff requests, there might be further macro calls. They can originate from a macro package (see roff(7) for an overview) or from a preprocessor. Preprocessor macros are easy to be recognized. They enclose their code into a pair of characteristic macros. +--------------+-------------+------------+ | preprocessor | start macro | end macro | +--------------+-------------+------------+ | eqn | .PS | .PE | | grap | .G1 | .G2 | | grn | .GS | .GE | | pic | .PS | .PE | | refer | .R1 | .R2 | | soelim | none | none | | tbl | .TS | .TE | +--------------+-------------+------------+ ESCAPE SEQUENCES Escape sequences are in-line language elements usually introduced by a backslash `\' and followed by an escape name and sometimes by a required argument. Input processing is continued directly after the escaped charac- ter or the argument resp. without an intervening separation character. So there must be a way to determine the end of the escape name and the end of the argument. This is done by enclosing names (escape name and arguments consisting of a variable name) by a pair of brackets [name] and constant arguments (number expressions and characters) by apostrophes (ASCII 0x27) like 'constant'. There are abbreviations for short names. Two character escape names can be specified by an opening parenthesis like \(xy without a closing counter- part. And all one-character names different from the special characters `[' and `(' can even be specified without a marker in the form \c. Constant arguments of length 1 can omit the marker apostrophes, too, but there is no two-character analogue. While 1-character escape sequences are mainly used for in-line functions and system related tasks, the 2-letter names following the \( construct are used for special characters predefined by the roff system. Escapes se- quences with names of more than two characters \[name] denote user defined named characters (see the char request). Single Character Escapes
NAME | DESCRIPTION | GROFF ELEMENTS | CONTROL CHARACTERS | NUMERICAL EXPRESSIONS | CONDITIONS | REQUESTS | ESCAPE SEQUENCES
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