title: Partial commit with Git
author: depierre
published: 2014-05-10
categories: Trick
keywords: trick, git, add, patch, commit


Have you ever been in a situation where you are constantly using a tool and you
feel like it misses an important feature for you?

Well a couple of days ago I felt like you with Git but not anymore thanks to
`git add --patch`!

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I constantly use Git. It offers so many essential features that I use it for
everything:

+ A new project? Git
+ A new report? Git
+ A new presentation? Git
+ A new blog post? Git
+ Some (non-binary) files you want to share with a friend? Git
+ Some dot-files you want to keep online? Git

That is to say that without Git, my life would be really sad :(

# My problem

I have a bad habit when I code though.

I am really fond of the PEP8 because it offers really nice rules which give
good looking code and make reviews way easier. Because of that, I really try to
be constant when following these rules and when I see a line that break one of
them, I can't stop myself to fix it.

This means that I often have several things in one commit (new code plus pep8
fixes). I know that I should not since a commit should only deal with one and
only one thing.  
This article nicely explain how a commit should be:
[http://dev.solita.fi/2013/07/04/whats-in-a-good-commit.html](http://dev.solita.fi/2013/07/04/whats-in-a-good-commit.html).

But until a couple of days before, I never figured out how to avoid this
because I did not think that it was possible to partially commit a file with
Git (and I should be ashamed because it was obvious that this feature had to
exist!).

# Partial commit with git --patch

When reading the Git man page of the `add` command (for some unrelated
reasons), I stumbled onto this entry:

    :::man
    NAME
       git-add - Add file contents to the index

    . . .

    OPTIONS
        . . .
        -p, --patch
           Interactively choose hunks of patch between the index and the work
           tree and add them to the index. This gives the user a chance to
           review the difference before adding modified contents to the index.

           This effectively runs add --interactive, but bypasses the initial
           command menu and directly jumps to the patch subcommand. See
           “Interactive mode” for details.