troff(1) General Commands Manual troff(1)
Name
troff - GNU roff typesetter and document formatter
Synopsis
troff [-abcCEiRSUz] [-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
Description
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.
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.
o Page breaks are marked by a phrase in angle brackets; for
example, "<beginning of page>".
o Lines are broken where they would be in formatted output.
o Vertical motion, apart from that implied by a break, is not
represented.
o 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.
o 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 Disable multi-color output and "color" request's ability to
enable it.
-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 Prevent loading of troffrc and troffrc-end; this option can be
useful for troubleshooting.
-S Enable safer mode and ignore any subsequent -U option.
-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,
put arbitrary content into troff output, or 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.
Warnings
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 unused | 11 2048 tab |
| 2 4 break | 12 4096 unused |
| 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 channel value 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 read 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. . 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, troff issues at most one
warning 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.
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, the formatter
automatically defines it with a value of 0. . So,
unless it is later deleted, GNU troff issues at
most one warning for each.
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; an attempt was made
to format characters or spaces on an input line
after an output line continuation escape sequence;
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 escape sequence or conditional
expression operator was used while in compatibility
mode.
tab 2048 A tab character appeared in a parameterized escape
sequence, in an unquoted macro argument, or where a
request expected a numeric expression 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.
Exit status
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.
Environment
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 (/opt/
local/share/groff/site-font), a standard location (/opt/local/
share/groff/1.24.1/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 (/opt/local/share/groff/site-tmac), and a standard
location (/opt/local/share/groff/1.24.1/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.
Files
/opt/local/share/groff/1.24.1/tmac/troffrc
is an initialization macro file loaded before any macro packages
specified with -m options.
/opt/local/share/groff/1.24.1/tmac/troffrc-end
is an initialization macro file loaded after all macro packages
specified with -m options.
/opt/local/share/groff/1.24.1/tmac/name.tmac
are macro files distributed with groff.
/opt/local/share/groff/1.24.1/font/devname/DESC
describes the output device name.
/opt/local/share/groff/1.24.1/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.
Authors
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 <wl@gnu.org>, Bernd Warken <groff-bernd.warken-72@web
.de>, and G. Branden Robinson <g.branden.robinson@gmail.com>.
See also
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.
groff 1.24.1 2026-05-15 troff(1)
groff 1.24.1 - Generated Mon May 18 15:43:27 CDT 2026