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)