Is it possible to stop the editor from popping up once git prepare-commit-msg hook is called?

Question

I am writing a prepare-commit-msg hook, which interactively prompts the user about some data and creates a commit message in a predefined format. In almost all cases, there is no need for the user to further edit the commit message. So is it possible to inform git not to open the editor once this hook is exited, and directly perform a commit with whatever is in the temporary msg file?

Answer 1

In Git, the value of the core.editor configuration controls whether the editor opens or closes once the prepare-commit-msg hook is called. Following the execution of the hook, Git will launch the defined editor if the core.editor configuration is set.

The following actions can be taken to stop the editor from opening following the prepare-commit-msg hook:

1. Temporarily unset core.editor in your hook script:

Inside your prepare-commit-msg hook script, you can unset the core.editor configuration temporarily before you finish the script. This way, Git won't open the editor even if it's configured.

This approach saves the original core.editor setting, unsets it for the duration of your script, and then restores it before exiting.

2. Use git commit with the -m option:

Instead of relying on the default behavior of Git to open the editor, you can use the git commit command with the -m option to specify the commit message directly.

Answer 2

Git looks in a series of places to find the editor to use when the user is expected to interactively configure content in an editor.

One of these is the core.editor configuration setting, but if none is present it then checks GIT_EDITOR, then VISUAL (if you're connected to a non-dumb terminal), then EDITOR, and finally falls back to a value hardcoded in at compile time (if not overridden by your distro's packaging, the default fallback is vi).

The easy answer, then, is to run git with GIT_EDITOR=: exported in the environment (: is a command identical to /bin/true, and this synonym is used in git/commit.c:run_commit_hook when git wants to inform a hook that no editor will be used).

That said, that variable needs to be exported before the copy of git that invokes your hook is started; you can't set it from within the hook.