gdiffmk [ -aaddmark ] [ -cchangemark ] [ -ddeletemark ] [ -D [ -B ]
           [ -Mmark1 mark2 ] ] [ -xdiffcmd ] [ -- ] [ --help ]
           [ --version ] file1 file2 [ output ]


   gdiffmk  compares  two groff(1), nroff(1), or troff(1) documents, file1
   and file2, and creates an output which  is  file2  with  added  `margin
   character' (.mc) commands that indicate the differences.

   If  the output filename is present, the output is written there.  If it
   is - or absent the output is written to the standard output.

   If the file1 or file2 argument is - the standard input is read for that
   input.  Clearly both cannot be -.

   Note  that  the  output  is  not  necessarily compatible with all macro
   packages and all preprocessors.  See the BUGS section below.


          Use the addmark for source lines not in  file1  but  present  in
          file2.  Default: +.

   -B     By  default,  the deleted texts marked by the -D option end with
          an added troff break command, .br, to ensure that the  deletions
          are  marked  properly.   This  is the only way to guarantee that
          deletions and small changes get flagged.   This  option  directs
          the program not to insert these breaks; it makes no sense to use
          it without -D.

          Use the changemark for changed source lines.  Default: |.

          Use the deletemark for deleted source lines.  Default: *.

   -D     Show  the  deleted  portions  from  changed  and  deleted  text.
          Default delimiting marks: [[ ... ]].

   -Mmark1 mark2
          Change  the  delimiting  marks  for  the -D option.  It makes no
          sense to use this option without -D.

          Use the diffcmd command to perform the comparison of  file1  and
          file2.  In particular, diffcmd should accept the GNU diff -Dname
          option.  Default: diff(1).

   --     All the following arguments are treated as file names,  even  if
          they begin with -.

   --help Print a usage message on standard error output and exit.

          Print version information on the standard output and exit.


   The  output  is  not necessarily compatible with all macro packages and
   all preprocessors.  A  workaround  that  is  often  successful  against
   preprocessor  problems  is  to  run  gdiffmk  on  the output of all the
   preprocessors instead of the input source.

   gdiffmk relies on the -Dname option of GNU diff(1)  to  make  a  merged
   `#ifdef'  output  format.  It hasn't been tested whether other versions
   of diff(1) do support this option.  See also the -xdiffcmd option.

   Report bugs to  Include a complete, self-contained
   example that will allow the bug to be reproduced, and say which version
   of gdiffmk you are using.


   Copyright  2004-2014 Free Software Foundation, Inc.

   This file is part of the gdiffmk utility, which is  part  of  groff,  a
   free software project.

   You  can  redistribute and/or modify gdiffmk under the terms of the GNU
   General Public License as published by the  Free  Software  Foundation,
   either version 3 of the License, or (at your option) any later version.

   gdiffmk  is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of  MERCHANTABILITY  or
   FITNESS  FOR  A PARTICULAR PURPOSE.  See the GNU General Public License
   for more details.

   You should have received a copy of the GNU General Public License along
   with this program.  If not, see <>.


   This document was written and is maintained by Mike Bianchi


   groff(1), nroff(1), gtroff(1), diff(1)


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