Commit Part of a File in Git

You’ve been working on a big set of changes, and haven’t committed to Git yet. Now, you want to commit some, but not all, changes to a file. Let’s look at adding patches.

Here’s the command.

$ g i t a d d - p a t c h

--patch lets you interactively choose which changes to apply to a commit.

Applying Patches

Run this command and you’ll see the following:

$ git add --patch
diff --git a/README.md b/README.md
index 18d277a..b012031 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # [jakeworth][production-url]

+A blog of awesome Git tricks.
+
(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,?]? ?

This is a piece of our diff, or a ‘hunk’, with information telling us which one we are currently reviewing (one of two), and a menu of options.

Type ?, to learn about each option.

y n q a d g j J e ? - - - - - - - - - - - s d q s d s s l l m p t o u t o e e e e a r a i a l a a a n i g n t g n e r v v u n e o ; e o c c e e a t t t t h l t d t t t l h h s o h s a f h h y e i t i t o i i l s a n s a h r s s e p g o g u d h e t h e n a h h i u u k u u t n t s n t h n n k h t k h t u k k t i a i o n h s g a s k u u e e n g n n h d h o m d d c u t u a e e u n h a n t t c c r k i l k o c i i r s l h d d e o i e e n h l r n d d t u a g , , n t a h k e n t s s u r y h e e n o e e e k r h o u f g n n a n i e e n k t v x x y s h e t t e n o i u h f n l r n u a e d n t t t g e k h h e e c e e r x i d r f h e e i u d m l n a e k h i s u n n i i k n n g t o h n e e s f i l e

What you do next is up to you. I approach this with the following thought process:

  1. Am I seeing too many changes at once? Or, would I like to keep some but not all of them? Split the hunks with s to consider each separately.
  2. For each hunk, do I want to commit it now? y or n.
  3. Or, do I know I want to add all the changes to the file? a.
  4. Or, discard the changes to the file? d.
  5. Do I want to edit this change? e, although this can be tricky if you aren’t comfortable editing diffs.

Consider each hunk, then commit the hunks you said y, or a, e to with:

$ g i t c o m m i t

Going Further

This is the only way that I commit, even for small changes. Why? I find it’s a nice default. And even for those small changes, I often am surprised to realize that I can break them down even more when reviewing them one-by-one.

To help, I’ve aliased this to gap, a trick I picked up at Hashrocket.

a l i a s g a p = ' g i t a d d - p a t c h '

This flag also applies to git checkout, which is handy. Use it to checkout changes to a file, in pieces:

$ g i t c h e c k o u t - p a t c h