git merge-file incorporates all changes that lead from the <base-file> to <other-file> into <current-file>. The result ordinarily goes into <current-file>. git merge-file is useful for combining separate changes to an original. Suppose <base-file> is the original, and both <current-file> and <other-file> are modifications of <base-file>, then git merge-file combines both changes.
A conflict occurs if both <current-file> and <other-file> have changes in a common segment of lines. If a conflict is found, git merge-file normally outputs a warning and brackets the conflict with lines containing <<<<<<< and >>>>>>> markers. A typical conflict will look like this:
lines in file A
lines in file B
If there are conflicts, the user should edit the result and delete one of the alternatives. When --ours, --theirs, or --union option is in effect, however, these conflicts are resolved favouring lines from <current-file>, lines from <other-file>, or lines from both respectively. The length of the conflict markers can be given with the --marker-size option.
The exit value of this program is negative on error, and the number of conflicts otherwise (truncated to 127 if there are more than that many conflicts). If the merge was clean, the exit value is 0.
git merge-file is designed to be a minimal clone of RCS merge; that is, it implements all of RCS merges functionality which is needed by git(1).