git-squash

#!/bin/bash

# from https://github.com/sheerun/git-squash/blob/e87fb1d410edceec3670101e2cf89297ecab5813/git-squash

set -e

CURRENT_BRANCH="$(git rev-parse --abbrev-ref HEAD)"
TEMP_BRANCH="temp$(date +%s)"

if [ "$1" == "" ]; then
  echo "Squashes all commits just like GitHub squash merge"
  echo ""
  echo "Usage: git squash <branch>"
  echo ""
  echo "Examples"
  echo " - git squash master"
  exit 1
fi

if [ "$(git status -s -uno)" != "" ]; then
  echo "Please commit all changes before squashing"
  exit 1
fi

if ! git show-ref "$1" > /dev/null; then
  echo "Branch $1 does not exist"
  exit 1
fi

FIRST_COMMIT_ID=$(git log $1.. --no-merges --pretty=format:%h | tail -1)

if [ "$FIRST_COMMIT_ID" == "" ]; then
  echo "There are no changes to be squashed"
  exit 1
fi

git checkout -q -b "$TEMP_BRANCH" "$1"

function finish {
  git checkout -q --force "$CURRENT_BRANCH"
  git branch -q -D "$TEMP_BRANCH"
}
trap finish EXIT

git merge --squash "$CURRENT_BRANCH"

git add -A

git commit -q -c "$FIRST_COMMIT_ID"

git checkout -q "$CURRENT_BRANCH"

git reset -q --hard "$TEMP_BRANCH"