NAME

       gdiffmk - mark differences between groff/nroff/troff files

SYNOPSIS

       gdiffmk [-a addmark] [-c changemark] [-d deletemark] [-D [-B] [-M mark1 mark2]]
               [-x diffcmd] [--] file1 file2 [output]

       gdiffmk --help

       gdiffmk --version

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 section “Bugs” 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.

AUTHORS

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

SEE ALSO

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