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Name | Synopsis | Description | Options | Warnings | Exit status | Environment | Files | Authors | See also | COLOPHON |
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troff(1) General Commands Manual troff(1)
troff - GNU roff typesetter and document formatter
troff [-abcCEiRUz] [-d ctext] [-d string=text] [-f font-family]
[-F font-directory] [-I inclusion-directory] [-m macro-
package] [-M macro-directory] [-n page-number] [-o page-
list] [-r cnumeric-expression] [-r register=numeric-
expression] [-T output-device] [-w warning-category]
[-W warning-category] [file ...]
troff --help
troff -v
troff --version
GNU troff transforms groff(7) language input into the device-
independent page description language detailed in groff_out(5);
troff is thus the heart of the GNU roff document formatting
system. If no file operands are present, or if file is “-”, troff
reads the standard input stream.
GNU troff is functionally compatible with the AT&T troff
typesetter and features numerous extensions. Many people prefer
to use the groff(1) command, a front end which also runs
preprocessors and output drivers in the appropriate order and with
appropriate options.
-h and --help display a usage message, while -v and --version show
version information; all exit afterward.
-a Generate a plain text approximation of the typeset output.
The read-only register .A is set to 1. This option
produces a sort of abstract preview of the formatted
output.
• Page breaks are marked by a phrase in angle brackets;
for example, “<beginning of page>”.
• Lines are broken where they would be in formatted
output.
• Vertical motion, apart from that implied by a break, is
not represented.
• A horizontal motion of any size is represented as one
space. Adjacent horizontal motions are not combined.
Supplemental inter-sentence space (configured by the
second argument to the .ss request) is not represented.
• A special character is rendered as its identifier
between angle brackets; for example, a hyphen appears as
“<hy>”.
The above description should not be considered a
specification; the details of -a output are subject to
change.
-b Write a backtrace reporting the state of troff's input
parser to the standard error stream with each diagnostic
message. The line numbers given in the backtrace might not
always be correct, because troff's idea of line numbers can
be confused by requests that append to macros.
-c Start with color output disabled.
-C Enable AT&T troff compatibility mode; implies -c. See
groff_diff(7).
-d ctext
-d string=text
Define roff string c or string as text. c must be a one-
character identifier; string can be of arbitrary length.
Such assignments happen before any macro file is loaded,
including the startup file. Due to getopt_long(3)
limitations, c cannot be, and string cannot contain, an
equals sign, even though that is a valid character in a
roff identifier.
-E Inhibit troff error messages; implies -Ww. This option
does not suppress messages sent to the standard error
stream by documents or macro packages using tm or related
requests.
-f fam Use fam as the default font family.
-F dir Search in directory dir for the selected output device's
directory of device and font description files. See the
description of GROFF_FONT_PATH in section “Environment”
below for the default search locations and ordering.
-i Read the standard input stream after all named input files
have been processed.
-I dir Search the directory dir for files (those named on the
command line; in psbb, so, and soquiet requests; and in
“\X'ps: import'”, “\X'ps: file'”, and “\X'pdf: pdfpic'”
device extension escape sequences). -I may be specified
more than once; each dir is searched in the given order.
To search the current working directory before others, add
“-I .” at the desired place; it is otherwise searched last.
-I works similarly to, and is named for, the “include”
option of Unix C compilers.
-m mac Search for the macro package mac.tmac and read it prior to
any input. If not found, tmac.mac is attempted. See the
description of GROFF_TMAC_PATH in section “Environment”
below for the default search locations and ordering.
-M dir Search directory dir for macro files. See the description
of GROFF_TMAC_PATH in section “Environment” below for the
default search locations and ordering.
-n num Begin numbering pages at num. The default is 1.
-o list
Output only pages in list, which is a comma-separated list
of inclusive page ranges; n means page n, m-n means every
page between m and n, -n means every page up to n, and n-
means every page from n on. troff stops processing and
exits after formatting the last page enumerated in list.
-r cnumeric-expression
-r register=numeric-expression
Define roff register c or register as numeric-expression.
c must be a one-character identifier; register can be of
arbitrary length. Such assignments happen before any macro
file is loaded, including the startup file. Due to
getopt_long(3) limitations, c cannot be, and register
cannot contain, an equals sign, even though that is a valid
character in a roff identifier.
-R Don't load troffrc and troffrc-end.
-T dev Prepare output for device dev. The default is ps; see
groff(1).
-U Operate in unsafe mode, enabling the cf, open, opena, pi,
pso, and sy requests, which are disabled by default because
they allow an untrusted input document to run arbitrary
commands and write to arbitrary file names. (GNU troff
does not, however, accept newlines (line feeds) in file
names supplied as arguments to requests.) This option also
adds the current directory to the macro package search
path; see the -m and -M options above.
-w cat
-W cat Enable and inhibit, respectively, warnings in category cat.
See section “Warnings” below.
-z Suppress formatted output.
GNU troff divides its warning diagnostics into named, numbered
categories. The -w and -W options use the associated names. A
power of two characterizes each category; the warn request and the
.warn register respectively set and report the sum of enabled
category codes. Warnings of each category are produced under the
following circumstances.
┌───────────────────────┬─────────────────────────────┐
│ Bit Code Category │ Bit Code Category │
├───────────────────────┼─────────────────────────────┤
│ 0 1 char │ 10 1024 reg │
│ 1 2 number │ 11 2048 tab │
│ 2 4 break │ 12 4096 right-brace │
│ 3 8 delim │ 13 8192 missing │
│ 4 16 unused │ 14 16384 input │
│ 5 32 scale │ 15 32768 escape │
│ 6 64 range │ 16 65536 space │
│ 7 128 syntax │ 17 131072 font │
│ 8 256 di │ 18 262144 ig │
│ 9 512 mac │ 19 524288 color │
│ │ 20 1048576 file │
└───────────────────────┴─────────────────────────────┘
break 4 A filled output line could not be broken such
that its length was less than or equal to, or
adjusted such that its length was exactly
equal to, the output line length “\n[.l]”.
GNU troff reports the amount of overset or
underset in the scaling unit configured by the
warnscale request in troff mode, and in ens
(‘n’; character cells) in nroff mode. This
category is enabled by default.
char 1 No user-defined character of the requested
name or index exists and no mounted font
defines a glyph for it, or input could not be
encoded for device-independent output. This
category is enabled by default.
color 524288 An undefined color name was selected, an
attempt was made to define a color using an
unrecognized color space, an invalid component
in a color definition was encountered, or an
attempt was made to redefine a default color.
delim 8 The selected delimiter character was ambiguous
because it is also meaningful when beginning a
numeric expression, or the closing delimiter
in an escape sequence was missing or
mismatched.
A future groff release may reject ambiguous
delimiters. In compatibility mode, ambiguous
delimiters are accepted without warning.
di 256 A di, da, box, or boxa request was invoked
without an argument when there was no current
diversion.
escape 32768 An unsupported escape sequence was
encountered.
file 1048576 An attempt was made to load a file that does
not exist, or a stream remained open at
formatter exit. This category is enabled by
default.
font 131072 A non-existent font was selected, or the
selection was ignored because a font selection
escape sequence was used after the output line
continuation escape sequence on an input line.
This category is enabled by default.
ig 262144 An invalid escape sequence occurred in input
ignored using the ig request. This warning
category diagnoses a condition that is an
error when it occurs in non-ignored input.
input 16384 An invalid character occurred on the input
stream.
mac 512 An undefined string, macro, or diversion was
used. When such an object is dereferenced, an
empty one of that name is automatically
created. So, unless it is later deleted, at
most one warning is given for each.
troff also uses this category to warn of an
attempt to move an unplanted trap macro. In
such cases, the unplanted macro is not
dereferenced, so it is not created if it does
not exist.
missing 8192 A request was invoked with a mandatory
argument absent.
number 2 An invalid numeric expression was encountered.
This category is enabled by default.
range 64 A numeric expression was out of range for its
context.
reg 1024 An undefined register was used. When an
undefined register is dereferenced, it is
automatically defined with a value of 0. So,
unless it is later deleted, at most one
warning is given for each.
right-brace 4096 A right brace escape sequence \} was
encountered where a number was expected.
scale 32 A scaling unit inappropriate to its context
was used in a numeric expression.
space 65536 A space was missing between a request or macro
and its argument. This warning is produced
when an undefined name longer than two
characters is encountered and the first two
characters of the name constitute a defined
name. No request is invoked, no macro called,
and an empty macro is not defined. This
category is enabled by default. It never
occurs in compatibility mode.
syntax 128 A self-contradictory hyphenation mode or
character flags were requested; an empty or
incomplete numeric expression was encountered;
an operand to a numeric operator was missing;
a recognized but inapposite escape sequence or
unprintable character code was used in a
device extension command; an attempt was made
to define a recursive, empty, or nonsensical
character class; or a groff extension
conditional expression operator was used while
in compatibility mode.
tab 2048 A tab character was encountered where a number
was expected, or appeared in an unquoted macro
argument.
Two warning names group other warning categories for convenience.
all All warning categories except di, mac, and reg. This
shorthand is intended to produce all warnings that are
useful with macro packages and documents written for AT&T
troff and its descendants, which have less fastidious
diagnostics than GNU troff.
w All warning categories. Authors of documents and macro
packages targeting groff are encouraged to use this
setting.
troff exits with status 0 on successful operation, status 2 if the
program cannot interpret its command-line arguments, and status 1
if it encounters a fatal error during operation, or is directed to
abort by the input.
GROFF_FONT_PATH and GROFF_TMAC_PATH each accept a search path of
directories; that is, a list of directory names separated by the
system's path component separator character. On Unix systems,
this character is a colon (:); on Windows systems, it is a
semicolon (;).
GROFF_FONT_PATH
A list of directories in which to seek the selected output
device's directory of device and font description files.
troff will scan directories given as arguments to any
specified -F options before these, then in a site-specific
directory (/usr/local/share/groff/site-font), a standard
location (/usr/local/share/groff/1.23.0/font), and a
compatibility directory (/usr/lib/font) after them.
GROFF_TMAC_PATH
A list of directories in which to search for macro files.
troff will scan directories given as arguments to any
specified -M options before these, then the current
directory (only if in unsafe mode), the user's home
directory, a site-specific directory (/usr/local/share/
groff/site-tmac), and a standard location (/usr/local/
share/groff/1.23.0/tmac) after them.
GROFF_TYPESETTER
Set the default output device. If empty or not set, ps is
used. The -T option overrides GROFF_TYPESETTER.
SOURCE_DATE_EPOCH
A timestamp (expressed as seconds since the Unix epoch) to
use as the output creation timestamp in place of the
current time. The time is converted to human-readable form
using gmtime(3) and asctime(3) when the formatter starts up
and stored in registers usable by documents and macro
packages.
TZ The time zone to use when converting the current time to
human-readable form; see tzset(3). If SOURCE_DATE_EPOCH is
used, it is always converted to human-readable form using
UTC.
/usr/local/share/groff/1.23.0/tmac/troffrc
is an initialization macro file loaded before any macro
packages specified with -m options.
/usr/local/share/groff/1.23.0/tmac/troffrc-end
is an initialization macro file loaded after all macro
packages specified with -m options.
/usr/local/share/groff/1.23.0/tmac/name.tmac
are macro files distributed with groff.
/usr/local/share/groff/1.23.0/font/devname/DESC
describes the output device name.
/usr/local/share/groff/1.23.0/font/devname/F
describes the font F of device name.
troffrc and troffrc-end are sought neither in the current nor the
home directory by default for security reasons, even if the -U
option is specified. Use the -M command-line option or the
GROFF_TMAC_PATH environment variable to add these directories to
the search path if necessary.
The GNU version of troff was originally written by James Clark; he
also wrote the original version of this document, which was
updated by Werner Lemberg ⟨[email protected]⟩, Bernd Warken ⟨groff-bernd
[email protected]⟩, and G. Branden Robinson ⟨g.branden.robinson@
gmail.com⟩.
Groff: The GNU Implementation of troff, by Trent A. Fisher and
Werner Lemberg, is the primary groff manual. You can browse it
interactively with “info groff”.
groff(1)
offers an overview of the GNU roff system and describes its
front end executable.
groff(7)
details the groff language, including a short but complete
reference of all predefined requests, registers, and escape
sequences.
groff_char(7)
explains the syntax of groff special character escape
sequences, and lists all special characters predefined by
the language.
groff_diff(7)
enumerates the differences between AT&T device-independent
troff and groff.
groff_font(5)
covers the format of groff device and font description
files.
groff_out(5)
describes the format of troff's output.
groff_tmac(5)
includes information about macro files that ship with
groff.
roff(7)
supplies background on roff systems in general, including
pointers to further related documentation.
This page is part of the groff (GNU troff) project. Information
about the project can be found at
⟨http://www.gnu.org/software/groff/⟩. If you have a bug report for
this manual page, see ⟨http://www.gnu.org/software/groff/⟩. This
page was obtained from the project's upstream Git repository
⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2025-08-11. (At
that time, the date of the most recent commit that was found in
the repository was 2025-08-09.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
groff 1.23.0.3821-a8b3f 2025-08-09 troff(1)
Pages that refer to this page: colcrt(1), man(1), zsoelim(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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