to add file to last commit
```plaintext
git add myfile
git commit --amend --no-edit    # add to previous commit
git commit --amend              # allow to change commit message
git config --global alias.car 'commit --amend --no-edit'
```

to unstage a file
```plaintext
git reset myfile      # will undo staging
```

more meaningful alias for reset
```plaintext
git config --global alias.unstage 'reset'
```

check out files from last commit
```plaintext
git checkout .     
```
note that this is destructive

undoing a commit
```plaintext
git reset --soft HEAD^
```

more meaningful name
```plaintext
git config --global alias.uncommit 'reset --soft HEAD^'
```

in vim:
```plaintext
:cq
```
quits with an error code (which will cause git to abort a commit)