Provided by: groff-base_1.23.0-3build2_amd64 bug

Name

       troff - GNU roff typesetter and document formatter

Synopsis

       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

Description

       GNU troff transforms groff(7) language input into  the  device-independent  output  format
       described  in  groff_out(5);  troff  is thus the heart of the GNU roff document formatting
       system.  If no file operands are given on the  command  line,  or  if  file  is  “-”,  the
       standard input stream is read.

       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.

              • 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 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 one character; string can be  of
              arbitrary  length.  Such string 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 control 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 name
              Process  the  file  name.tmac prior to any input files.  If not found, tmac.name 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 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  name;  register  can  be of arbitrary length.  Such register 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 open, opena, pi, pso, and sy  requests,  which
              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 package search path; see the -m and -M options above.

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

       -z     Suppress formatted output.

Warnings

       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   A filled output line could not be broken such that its length was less
                           than  the  output  line  length  \n[.l].   This category is enabled by
                           default.

       char            1   No mounted font defines a glyph for  the  requested  character.   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 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 diversion.

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

       escape      32768   An unsupported escape sequence was encountered.

       file      1048576   An attempt was made to load a file that does not exist.  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.

                           This warning is also emitted upon 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  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 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.

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 (/usr/
              share/groff/site-font), a standard location (/usr/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/share/groff/site-tmac), and  a  standard  location  (/usr/
              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.

Files

       /usr/share/groff/1.23.0/tmac/troffrc
              is  an initialization macro file loaded before any macro packages specified with -m
              options.

       /usr/share/groff/1.23.0/tmac/troffrc-end
              is an initialization macro file loaded after all macro packages specified  with  -m
              options.

       /usr/share/groff/1.23.0/tmac/name.tmac
              are macro files distributed with groff.

       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

       /usr/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.

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.