Re: Query on git commit amend

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 8, 2011, 17:52 UTC
Message-ID: <7vvcprar3v.fsf@alter.siamese.dyndns.org>
In-Reply-To: <4EDEFD66.4020404@st.com>

Viresh Kumar <viresh.kumar@st.com> writes:

Show 10 quoted lines

> GIT_EDITOR=cat git commit --amend
>
> over
>
> git commit --amend -C HEAD
>
> ?
>
> ...
> But for single commit probably second one looks easier. Isn't it?

I saw "--amend -C HEAD" mentioned in some newbie-guide webpages, and I think you just copy/learned from one of them, so it is not entirely your fault, but the combination of --amend and "-C HEAD" is an idiotic thing that happens to work, if you think about what exactly you are telling to the command.

The point of --amend is twofold. One is to let you tweak the contents of what is committed, which is not the topic of this thread, and the other is to allow the user to reuse the log message from the commit being amended, instead of typing the message from scratch.

The "-c <commit>" and its cousin "-C <commit>" options are about telling Git that the user does _not_ want the other usual logic to come up with the initial commit template (e.g. when committing anew, it may read the log template file, when committing a merge, it may read the MERGE_MSG prepared by fmt-merge-msg, and most importantly in this context, when amending, the one that is prepared by the --amend logic is used) kick in at all, and instead wants to start from the log message of the named commit.

So by saying "--amend -C HEAD" you are saying "I want to reuse the log message of the commit I am amending,... eh, scratch that, I instead want to use the log message of the HEAD commit", as if the commit you are amending and HEAD are two different things. That is idiotic.

And you say that only for the side effect that capital "-C" stops the editor.

Compared to that idiotic statement, "EDITOR=: git commit --amend" is a lot saner way to say the same thing in a more direct and straightforward way. "I want to reuse the log message of the commit I am amending, and the editor to use it while running that commit is the command 'true', i.e. the one that does not really touch any line in the text file and successfully exits, because I am not going to change anything".

Of course, if "git commit --amend" honoured "--no-edit", that is even more direct, straightforward and intuitive way to say so ;-)