git-merge-index - Run a merge for files needing merging

git merge-index [-o] [-q] <merge-program> (-a | ( [--] <file>...) )

This looks up the <file>(s) in the index and, if there are any merge entries, passes the SHA-1 hash for those files as arguments 1, 2, 3 (empty argument if no file), and <file> as argument 4. File modes for the three files are passed as arguments 5, 6 and 7.


Do not interpret any more arguments as options.


Run merge against all files in the index that need merging.


Instead of stopping at the first failed merge, do all of them in one shot - continue with merging even when previous merges returned errors, and only return the error code after all the merges.


Do not complain about a failed merge program (a merge program failure usually indicates conflicts during the merge). This is for porcelains which might want to emit custom messages.

If git merge-index is called with multiple <file>s (or -a) then it processes them in turn only stopping if merge returns a non-zero exit code.

Typically this is run with a script calling Git’s imitation of the merge command from the RCS package.

A sample script called git merge-one-file is included in the distribution.

ALERT ALERT ALERT! The Git "merge object order" is different from the RCS merge program merge object order. In the above ordering, the original is first. But the argument order to the 3-way merge program merge is to have the original in the middle. Don’t ask me why.


torvalds@ppc970:~/merge-test> git merge-index cat MM
This is MM from the original tree.              # original
This is modified MM in the branch A.            # merge1
This is modified MM in the branch B.            # merge2
This is modified MM in the branch B.            # current contents


torvalds@ppc970:~/merge-test> git merge-index cat AA MM
cat: : No such file or directory
This is added AA in the branch A.
This is added AA in the branch B.
This is added AA in the branch B.
fatal: merge program failed

where the latter example shows how git merge-index will stop trying to merge once anything has returned an error (i.e., cat returned an error for the AA file, because it didn’t exist in the original, and thus git merge-index didn’t even try to merge the MM thing).

Part of the git(1) suite

06/01/2024 Git 2.45.2