/mcls

Fixing Commits in Git

You can fix your last commit in git by doing git commit --amend. For example, if you had a typo in your last commit message you could correct it by doing:

Fixing a typo with –amend
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$ git commit -m "Oops, a typo"
$ git log --oneline
9e29e33 Oops, a typo

$ git commit --amend -m "New commit message without typos"
$ git log --oneline
aa7faf2 New commit message without typos

The previous commit will be replaced by the new one, which is based on the current contents of the index. For clarity, I’ll add that the git index is the staging area, also known as everything that is currently being tracked by git. So if you forgot to add some file to the index in the last commit, you could do:

Adding a file 
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$ git commit -am "Made some changes" # Forgot to add forgotten-file.txt
$ git add forgotten-file.txt
$ git commit --amend -m "Made some changes and added forgotten-file.txt"

Already pushed the commit?

If you’ve already pushed your faulty commit then it’s also best to first do something like: git push -f origin HEAD^:master. Pushing your HEAD at the previous commit and then doing the amend will prevent you from having to do a pull & merge just to fix something small like a typo.

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$ git commit -am "Typo"
$ git push
$ # Realize you had a typo, so push again but send HEAD^ upstream 
$ # ( HEAD^ means the HEAD at the previous commit )
$ git push -f origin HEAD^:master
$ git commit --amend -m "Fixed Typo"
$ git push # No pull or merge needed

Documentation

Lastly here’s the --amend option documentation from the git-commit man page.

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--amend
    Used to amend the tip of the current branch. Prepare the tree object you would want to replace
    the latest commit as usual (this includes the usual -i/-o and explicit paths), and the commit
    log editor is seeded with the commit message from the tip of the current branch. The commit
    you create replaces the current tip - if it was a merge, it will have the parents of the
    current tip as parents - so the current top commit is discarded.
    It is a rough equivalent for:

        $ git reset --soft HEAD^
        $ ... do something else to come up with the right tree ...
        $ git commit -c ORIG_HEAD

    but can be used to amend a merge commit.
    You should understand the implications of rewriting history if you amend a commit that has
    already been published. (See the "RECOVERING FROM UPSTREAM REBASE" section in git-rebase(1).)