troff(1) — Linux manual page

Name | Synopsis | Description | Options | Warnings | Environment | Files | Authors | See Also | COLOPHON

troff(1)                   General Commands Manual                  troff(1)

Name         top

       troff - the troff processor of the groff text formatting system

Synopsis         top

       troff [-abcivzCERU] [-d cs] [-f fam] [-F dir] [-I dir] [-m name]
             [-M dir] [-n num] [-o list] [-r cn] [-T name] [-w name]
             [-W name] [file ...]

Description         top

       This manual page describes the GNU version of troff.  It is part of
       the groff document formatting system.  It is functionally compatible
       with Unix troff, but has many extensions, see groff_diff(7).  Usually
       it should be invoked using the groff(1) command which will also run
       preprocessors and postprocessors in the appropriate order and with
       the appropriate options.

Options         top

       Whitespace is permitted between a command-line option and its

       -a     Generate an ASCII (Unicode basic Latin) approximation of the
              typeset output.  The read-only register .A is set to 1.  On a
              system using the man-db manual page formatter and that
              installs man pages compressed with gzip(1), one might use the
              shell command
                     zcat $(man -w troff) | groff -a -t -man -Tdvi | less
              to observe how lines are broken for the DVI device.

       -b     Print a backtrace with each warning or error message.  This
              backtrace should help track down the cause of the error.  The
              line numbers given in the backtrace may not always be correct,
              for troff's idea of line numbers gets confused by as or am

       -c     Disable color output (always disabled in compatibility mode).

       -C     Enable compatibility mode.

              Define c or name to be a string s; c must be a one letter

       -E     Inhibit all error messages of troff.  Note that this doesn't
              affect messages output to standard error by macro packages
              using the tm or tm1 requests.

       -ffam  Use fam as the default font family.

       -Fdir  Search in directory (or directory path) dir for subdirectories
              devname (name is the name of the device) and there for the
              DESC file and font files.  dir is scanned before all other
              font directories.

       -i     Read the standard input after all the named input files have
              been processed.

       -Idir  This option may be used to add a directory to the search path
              for files (both those on the command line and those named in
              .psbb requests).  The search path is initialized with the cur‐
              rent directory.  This option may be specified more than once;
              the directories are then searched in the order specified (but
              before the current directory).  If you want to make the cur‐
              rent directory be read before other directories, add -I. at
              the appropriate place.

              No directory search is performed for files with an absolute
              file name.

       -mname Read in the file name.tmac.  If it isn't found, try
              instead.  It will be first searched for in directories given
              with the -M command-line option, then in directories given in
              the GROFF_TMAC_PATH environment variable, then in the current
              directory (only if in unsafe mode), the home directory, /usr/
              local/lib/groff/site-tmac, /usr/local/share/groff/site-tmac,
              and /usr/local/share/groff/1.22.4/tmac.

       -Mdir  Search directory (or directory path) dir for macro files.
              This is scanned before all other macro directories.

       -nnum  Number the first page num.

       -olist 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 means print every page up to n, n- means
              print every page from n.  troff will exit after printing the
              last page in the list.

              Set number register c or name to n; c must be a one character
              name; n can be any troff numeric expression.

       -R     Don't load troffrc and troffrc-end.

       -Tname Prepare output for device name, rather than the default ps;
              see groff(1) for a more detailed description.

       -U     Unsafe mode.  This will enable the following requests: open,
              opena, pso, sy, and pi.  For security reasons, these poten‐
              tially dangerous requests are disabled otherwise.  It will
              also add the current directory to the macro search path.

       -v     Print the version number.

       -wname Enable warning name.  Available warnings are described in sec‐
              tion “Warnings” below.  To enable most useful warnings use -w
              all.  To enable absolutely all warnings use -w w instead.
              Multiple -w options are allowed.

       -Wname Inhibit warning name.  Multiple -W options are allowed.

       -z     Suppress formatted output.

Warnings         top

       The warnings that can be given by troff are divided into the
       following categories.  The name associated with each warning is used
       by the -w and -W options; the number is used by the warn request, and
       by the .warn register; it is always a power of 2 to allow bitwise

               │Bit   Code   Warning │ Bit    Code       Warning   │
               │  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   In fill mode, lines which could not be broken so
                           that their length was less than the line length.
                           This is enabled by default.

       char            1   Non-existent characters.  This is enabled by

       color      524288   Color-related warnings.

       delim           8   Missing or mismatched closing delimiters.

       di            256   Use of di or da without an argument when there is
                           no current diversion.

       el             16   Use of the el request with no matching ie

       escape      32768   Unrecognized escape sequences.  When an
                           unrecognized escape sequence is encountered, the
                           escape character is ignored.

       file      1048576   Indicates a missing file for the mso request.
                           Enabled by default.

       font       131072   Non-existent fonts.  This is enabled by default.

       ig         262144   Invalid escapes in text ignored with the ig
                           request.  These are conditions that are errors
                           when they do not occur in ignored text.

       input       16384   Invalid input characters.

       mac           512   Use of undefined strings, macros and diversions.
                           When an undefined string, macro or diversion is
                           used, that string is automatically defined as
                           empty.  So, in most cases, at most one warning
                           will be given for each name.

       missing      8192   Requests that are missing non-optional arguments.

       number          2   Invalid numeric expressions.  This is enabled by

       range          64   Out of range arguments.

       reg          1024   Use of undefined number registers.  When an
                           undefined number register is used, that register
                           is automatically defined to have a value of 0.
                           So, in most cases, at most one warning will be
                           given for use of a particular name.

       right-brace  4096   Use of \} where a number was expected.

       scale          32   Meaningless scaling indicators.

       space       65536   Missing space between a request or macro and its
                           argument.  This warning will be given when an
                           undefined name longer than two characters is
                           encountered, and the first two characters of the
                           name make a defined name.  The request or macro
                           will not be invoked.  When this warning is given,
                           no macro is automatically defined.  This is
                           enabled by default.  This warning will never
                           occur in compatibility mode.

       syntax        128   Dubious syntax in numeric expressions.

       tab          2048   Inappropriate use of a tab character.  Either use
                           of a tab character where a number was expected,
                           or use of tab character in an unquoted macro

       There are also names that can be used to refer to groups of warnings:

       all    All warnings except di, mac, and reg.  It is intended that
              this covers all warnings that are useful with traditional
              macro packages.

       w      All warnings.

Environment         top

              A colon separated list of directories in which to search for
              macro files.  troff will scan directories given in the -M
              option before these, and in standard directories (current
              directory if in unsafe mode, home directory, /usr/local/lib/
              groff/site-tmac, /usr/local/share/groff/site-tmac, /usr/local/
              share/groff/1.22.4/tmac) after these.

              Default device.

              A colon separated list of directories in which to search for
              the devname directory.  troff will scan directories given in
              the -F option before these, and in standard directories (/usr/
              local/share/groff/site-font, /usr/local/share/groff/1.22.4/
              font, /usr/lib/font) after these.

Files         top

              Initialization file (called before any other macro package).

              Initialization file (called after any other macro package).

              Macro files

              Device description file for device name.

              Font file for font F of device name.

       Note that troffrc and troffrc-end are searched for neither in the
       current nor the home directory by default for security reasons (even
       if the -U option is given).  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 modified
       by Werner Lemberg ⟨⟩ and Bernd Warken

See Also         top

              The main program of the groff system, a wrapper around troff.

              A description of the groff language, including a short but
              complete reference of all predefined requests, registers, and
              escapes of plain groff.  From the command line, this is called

                     man 7 groff

              The differences of the groff language and the classical troff
              language.  Currently, this is the most actual document of the
              groff system.

              An overview over groff and other roff systems, including
              pointers to further related documentation.

       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”.

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 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-12.)  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           14 June 2020                        troff(1)

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