8.1 Selecting Which Changes to Incorporate

You can select all unmerged changes from older to yours for merging into mine with the ‘-e’ or ‘--ed’ option. You can select only the nonoverlapping unmerged changes with ‘-3’ or ‘--easy-only’, and you can select only the overlapping changes with ‘-x’ or ‘--overlap-only’.

The ‘-e’, ‘-3’ and ‘-x’ options select only unmerged changes, i.e. changes where mine and yours differ; they ignore changes from older to yours where mine and yours are identical, because they assume that such changes have already been merged. If this assumption is not a safe one, you can use the ‘-A’ or ‘--show-all’ option (see section Marking Conflicts).

Here is the output of the command diff3 with each of these three options (see section A Third Sample Input File, for the complete contents of the files). Notice that ‘-e’ outputs the union of the disjoint sets of changes output by ‘-3’ and ‘-x’.

Output of ‘diff3 -e lao tzu tao’:

11a

  -- The Way of Lao-Tzu, tr. Wing-tsit Chan
.
8c
  so we may see their result.
.

Output of ‘diff3 -3 lao tzu tao’:

8c
  so we may see their result.
.

Output of ‘diff3 -x lao tzu tao’:

11a

  -- The Way of Lao-Tzu, tr. Wing-tsit Chan
.