troff(1) — Linux manual page

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troff(1)                 General Commands Manual                troff(1)

Name         top

       troff - GNU roff typesetter and document formatter

Synopsis         top

       troff [-abcCEiRUz] [-d cs] [-d name=string] [-f fam] [-F dir]
             [-I dir] [-m name] [-M dir] [-n num] [-o list] [-r cn]
             [-r reg=expr] [-T dev] [-w name] [-W name] [file ...]

       troff --help

       troff -v
       troff --version

Description         top

       The GNU version of troff is the heart of the groff document
       formatting system.  troff is the groff system's formatter, the
       program that transforms roff language input into a device-
       independent output format.  It 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         top

       -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

              •      Page breaks are marked by a phrase in angle
                     brackets; for example, “<beginning of page>”.

              •      Lines are broken where they would be in the
                     formatted output.

              •      A horizontal motion of any size is represented as
                     one space.  Adjacent horizontal motions are not
                     combined.  Inter-sentence space nodes (those
                     arising from the second argument to the .ss
                     request) are not represented.

              •      Vertical motions are not represented.

              •      Special characters are rendered in angle brackets;
                     for example, the default soft hyphen character
                     appears as “<hy>”.

              The above description should not be considered a
              specification; the details of -a output are subject to

       -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 strings
              or macros.

       -c     Start with color output disabled.

       -C     Enable AT&T troff compatibility mode; implies -c.

       -d cs
       -d name=string
              Define roff string c or name as s or string; c must be a
              one-character name.  Due to getopt_long(3) limitations,
              c cannot be and name 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

       -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 after all the named input files
              have been processed.

       -I dir Search dir for input files (those on the command line,
              those named in .psbb, .so, and .soquiet requests, and
              those named in “\X'ps: import'”, “\X'ps: file'”, and
              “\X'pdf: pdfpic'” escape sequences).  This option may be
              specified more than once; the directories are then
              searched in the order specified.  If you want to search
              the current directory before others, add “-I .” at the
              appropriate place.  The current working directory is
              otherwise searched last.  -I works similarly to, and is
              named for, the “include” option of Unix C compilers.  No
              directory search is performed for files specified using an
              absolute file name.

       -m name
              Process name.tmac before any input files.  If name.tmac is
              not found, is attempted.  name (in both
              arrangements) is presumed to be a macro file; 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 Number the first page num.

       -o list
              Output only pages in list, which is a comma-separated list
              of page ranges; n means print page n, m-n means print
              every page between m and n, n, -n means print every page
              up to n, and n- means print every page from n on.  troff
              stops processing and exits after formatting the last page
              enumerated in list.

       -r cn
       -r reg=n
              Define roff register c or reg as groff numeric
              expression n or expr; c must be a one-character name.  Due
              to getopt_long(3) limitations, c cannot be and reg 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, rather than the default,
              “ps”; see groff(1).

       -U     Operate in unsafe mode, which enables the .open, .opena,
              .pi, .pso, and .sy requests.  These requests are disabled
              by default because they allow an untrusted input document
              to write to arbitrary file names and run arbitrary
              commands.  This option also adds the current directory to
              the macro search path; see the -m option above.

       -w name
       -W name
              Enable (-w) or inhibit (-W) emission of warnings in
              category name.  See section “Warnings” below.

       -z     Suppress formatted output.

Warnings         top

       Warning diagnostics emitted by troff are divided into named,
       numbered categories.  The name associated with each warning
       category is used by the -w and -W options.  Each category is also
       assigned a power of two; the sum of enabled category codes is
       used by the warn request and the .warn register.  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   el       │  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   When filling is enabled, a line could not be
                           broken such that its length was less than the
                           output line length \n[.l].  This is enabled
                           by default.

       char            1   An undefined glyph was requested for output.
                           (“char” is a misnomer since it reports
                           missing glyphs—there are no “missing” input
                           characters, only invalid ones.)  This
                           cateogry is enabled by default.

       color      524288   An undefined color was dereferenced, 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 the default color.

       delim           8   The closing delimiter in an escape sequence
                           was missing or mismatched.

       di            256   A di, da, box, or boxa request was invoked
                           without an argument when there was no current

       el             16   The el request was encountered with no prior
                           corresponding ie request.

       escape      32768   An unsupported escape sequence was
                           encountered.  In such a sequence \X, the
                           escape character is ignored and X is output.

       file      1048576   An attempt was made to load a file that does
                           not exist.  This category is enabled by

       font       131072   A non-existent font was dereferenced.  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

       mac           512   An undefined string, macro, diversion, or box
                           was used.  When such an object is
                           dereferenced, an empty object of that name is
                           automatically created.  So, in most cases, at
                           most one warning is given for each name.

                           This warning is also emitted upon an attempt
                           to move an unplanted trap.  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

       range          64   A numeric expression was out of range for its

       reg          1024   An undefined register was used.  When an
                           undefined register is dereferenced, it is
                           automatically defined with a value of 0.  So,
                           in most cases, at most one warning is given
                           for each name.

       right-brace  4096   A right brace escape sequence \} was
                           encountered where a number was expected.

       scale          32   An inappropriate scaling indicator 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

       syntax        128   A self-contradictory hyphenation mode was
                           requested; an empty or incomplete numeric
                           expression was encountered; an operand to a
                           numeric operator was missing; 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 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

Environment         top

       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 (;).

              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.

              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 platform-specific directory (/usr/local/lib/
              groff/site-tmac), a site-specific directory (/usr/local/
              share/groff/site-tmac), and a standard location (/usr/
              local/share/groff/1.23.0/tmac) after them.

              Set the default output device.  If empty or not set, “ps”
              is used.  The -T option overrides GROFF_TYPESETTER.

              A timestamp (expressed as seconds since the Unix epoch) to
              use as the creation timestamp in place of the current
              time.  The time is converted to human-readable form using
              ctime(3) when the formatter starts up and stored in
              registers usable by documents and macro packages.

       TZ     The timezone to use when converting the current time (or
              value of SOURCE_DATE_EPOCH) to human-readable form; see

Files         top

              is an initialization macro file loaded before any macro
              packages specified with -m options.

              is an initialization macro file loaded after all macro
              packages specified with -m options.

              are macro files distributed with groff.

              describes the output device name.

              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         top

       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 ⟨⟩, Bernd Warken ⟨groff-bernd⟩, and G. Branden Robinson ⟨g.branden.robinson@⟩.

See also         top

       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”.

              offers an overview of the GNU roff system and describes
              its front end executable.

              details the groff language, including a short but complete
              reference of all predefined requests, registers, and
              escape sequences.

              explains the syntax of groff special character escape
              sequences, and lists all special characters predefined by
              the language.

              enumerates the differences between AT&T device-independent
              troff and groff.

              covers the format of groff device and font description

              describes the format of troff's output.

              includes information about macro files that ship with

              supplies background on roff systems in general, including
              pointers to further related documentation.

COLOPHON         top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, see ⟨⟩.
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2021-08-27.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-08-23.)  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

groff 1.23.0.rc1.1101-d1263-di2r6tyAugust 2021                     troff(1)

Pages that refer to this page: colcrt(1)groffer(1)grops(1)man(1)zsoelim(1)groff_char(7)groff_trace(7)roff(7)