git-fmt-merge-msg

git fmt-merge-msg [-m ] [-F ] [ ]

-m
    Reads the primary merge description from file. This file typically contains the branch names and potentially a merge message header prepared by git merge.

-F
    Reads additional log message content from file. This is typically used in scenarios like squash merges, where a specific log message needs to be included in the merge commit.


    A short, user-friendly description of the base branch or commit that is being merged into. This is usually automatically generated by git merge.


    A short, user-friendly description of the branch or commit that is being merged. This is also typically automatically generated by git merge.

git-fmt-merge-msg is an internal Git plumbing command primarily used by git merge to generate the default merge commit message. It is not typically invoked directly by end-users. The command takes descriptions of the merged branches and, optionally, pre-existing merge message content and conflict information, then formats them into a standard merge commit log. It handles different merge scenarios, such as regular merges, fast-forward merges, and squash merges, adapting the message accordingly.

It often reads details from internal Git files like .git/MERGE_MSG, .git/MERGE_RR, and .git/MERGE_RR_OMIT to construct the final message, which includes details about the merged branches and any detected merge conflicts. Its purpose is to ensure a consistent and informative default message for merge commits, reducing manual effort for users.

This command is an internal Git plumbing command. It is typically invoked automatically by higher-level Git commands like git merge and is not intended for direct user interaction. As an internal command, its interface or behavior might change in future Git versions without strict backward compatibility guarantees, although it has been stable for a long time. Users should rely on git merge to generate their merge commit messages rather than trying to manually execute this command.

git-fmt-merge-msg is categorized as a "plumbing" command in Git. Plumbing commands are low-level commands that perform specific operations and are designed to be used as building blocks by "porcelain" (user-facing) commands or scripts. This means it is usually invoked by git merge behind the scenes, rather than directly by a user.

The command is responsible for constructing the default merge commit message based on information stored in the .git directory. This includes files like .git/MERGE_MSG (which contains the raw message for the merge), .git/MERGE_RR (details about merge conflict resolution), and .git/MERGE_RR_OMIT (paths that were removed due to conflicts). It intelligently combines these pieces of information to produce a readable and informative commit message that summarizes the merge operation and any conflicts.

The git-fmt-merge-msg command has been a fundamental part of Git's internal plumbing since the early days of the git merge command. It was introduced to provide a consistent and automated way to generate default merge commit messages. Over time, its core function of formatting merge descriptions into a commit message has remained a foundational piece of Git's merge workflow, adapting to new merge strategies or features (like squash merges) as they were introduced, but its fundamental role has been stable.

git-merge(1), git-commit(1), git-var(1)