Auto-fixup a previous git commit with the changes from your staging area

git-autofix

#!/bin/sh
# Auto-applies changes from the index to a previous commit
# eg 
#   git add foo
#   git autofix HEAD~3

#!/bin/sh

target="$(git rev-parse $1)"

if ! git commit --fixup=$target ; then
  echo "commit fail, aborting"
  exit 1
fi

dirty="$(git diff --name-only --exit-code HEAD)"

( test -z "$dirty" || git stash ) &&
  GIT_EDITOR=cat git rebase --interactive --autosquash $target~1 &&
  ( test -z "$dirty" || git stash pop )