Updated: 2021/Apr/14

GDIFFMK(1)                  General Commands Manual                 GDIFFMK(1)

       gdiffmk - mark differences between groff/nroff/troff files

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

       This document was written and is maintained by

       This document is distributed under the terms of the FDL (GNU Free
       Documentation License) version 1.1 or later.  You should have received
       a copy of the FDL on your system, it is also available on-line at the

       gdiffmk is part of the groff GNU free software project.  All parts of
       the groff package are protected by GNU copyleft licenses.  The software
       files are distributed under the terms of the GNU General Public License
       (GPL), while the documentation files mostly use the GNU Free
       Documentation License (FDL).

       Copyright (C) 2004, 2005 Free Software Foundation, Inc.

       gdiffmk is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2, 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 groff; see the file COPYING.  If not, write to the Free Software
       Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA.

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

Groff Version 1.19.2           September 4, 2005                    GDIFFMK(1)