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.

SEE ALSO

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

groff 1.22.4                                      23 March 2022                                       GDIFFMK(1)