git-merge-index

Run merge for unmerged files

$ git merge-index [merge-program] -a

$ git merge-index [merge-program] [file]

git merge-index [options] merge-program files...

git merge-index runs a specified merge program for each file needing merging. This low-level plumbing command is part of Git's internal merge machinery, invoked during three-way merge operations to handle unmerged files in the index.
The command passes file information (including base, ours, and theirs versions with their object IDs) to the specified merge program. Most users never need to call this directly, as `git merge` handles it automatically. It is exposed for custom merge workflows and understanding Git internals.

-a

Run on all unmerged entries.

Don't stop on error.

Quiet mode.

git-merge(1), git-mergetool(1)