NAME

       gdiffmk - mark differences between groff/nroff/troff files

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

       -aaddmark
              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.

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

       -ddeletemark
              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.

       -xdiffcmd
              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.

       --version
              Print version information on the standard output and exit.

BUGS

       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.

AUTHORS

       This document was written and is maintained by Mike Bianchi ⟨MBianchi@Foveal.com⟩.

       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
       GNU copyleft site ⟨http://www.gnu.org/copyleft/fdl.html⟩.

       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

       Copyright © 2004, 2005, 2008 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 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
       <http://www.gnu.org/licenses/>.

SEE ALSO

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