Pre-commit hooks getting partial committed file list

Question

I know running git-diff and other tools can identify the changes in the repository, but when I do a partial commit, I need to pass only the committed files (rather than the entire set of files that are touched) to the pre-commit hook.

For example, I modified three files and commit only two, and I want the pre-commit hook to know the name of the two files.

git status --porcelain

M A.c 
M B.c
M C.h

then I execute:

git commit -m "two files only" A.c B.c

How can the pre-commit hook get hold of the list of the two files only?

Answer 1

The pre-commit is run at the beginning of the commit process... @Vince's link is the one to look at. Once the hook is running, your script can use git diff --cached --name-only to get the names of the staged files within the pre-commit script. The command works even if the user had staged more for commit, but only requested to commit a subset of the files on the command line.

Answer 2

I think your question is more : when is the pre-commit hook triggered?

And [I just discovered hooks, it seems cool] apparently, pre-commit hook is triggered before you even run git commit (you can still try to hook up a "Hello World" script to it to see precisely when it is triggered).

But then what I can think of is the add command : git add -u A.c B.c (u stands for update). Once you've run it, commit command will commit these files (just run git commit -m mymessage)

I don't know exactly how you can retrieve the list of added files (via the index probably), but hopefully this will help you

Reference : http://git-scm.com/book/en/Customizing-Git-Git-Hooks