How to modify a specified commit?

Question

I usually submit a list of commits for review. If I have the following commits:

1. HEAD
2. Commit3
3. Commit2

Answer 1

If you haven't already pushed the commits then you can go back to a previous commit using git reset HEAD^[1,2,3,4...]

For example

git commit  -m "Updated files 1 and 2"
git commit  -m "Updated file 3"

Oops, forgot to add file2 to the first commit...

git reset HEAD^1 // because I only need to go back 1 commit

git add 

This will add file2 to the first commit.