GIT-MERGE-INDEX(1)

💅 NAME

git-merge-index — run a merge for files that need merging ✨ (yes, this is the Git Manual, and yes, it's about to get cute but stay accurate, bestie)

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🦋 SYNOPSIS

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

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🌸 DESCRIPTION

Okay so picture this, right: git merge-index goes and looks up the <file>(s) in the index, and if there are any merge entries chillin' in there, it passes the SHA-1 hash for those files as arguments 1, 2, and 3 (empty argument if there's no file, no drama), and <file> itself as argument 4. Then the file modes for those three files get passed as arguments 5, 6 and 7. That's the whole vibe. Seven arguments, every time, iconic. 🎀

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✨ OPTIONS ✨

• -- — okay bestie, this one's the vibe check: do not interpret any more arguments as options. Everything after is just files. periodt. 🫶
• -a — run merge against all the files in the index that need merging. Go off, queen. 🌈
• -o — instead of stopping at the first failed merge, do all of them in one shot — keep merging even when previous merges returned errors, and only return the error code after all the merges. Lowkey relentless. 💀
• -q — 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. Quiet queen behaviour. 🙈

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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. Ngl, that's just how it's done.

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. 😭

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👑 EXAMPLES

Examples, because you're a visual learner and I respect that:

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

or

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). Main character "I'm done here" energy. 💅🔥

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🌟 GIT

Part of the git(1) suite. iykyk ⭐

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Okay that's the whole page, bestie — you ate. 🫶 This was Git 2.56.0, dated 2026-09-27, and no cap, you now understand git-merge-index better than half the internet. 💖