easy git squash script

git-squash

#!/bin/bash
# Author: Joel Nothman

usage() {
  echo Usage: $0 '[-m <commit msg>] <base>'
  exit 1
}

unset base
unset message

while [ -n "$1" ]; do
  case "$1" in
  -h)
    usage
    ;;
  -m)
    shift
    if [ -z "$1" ]; then
      echo '-m requires an argument' >&2
      usage
    fi

    if [ -n "$message" ]; then
      message+=$'\n\n'"$1"
    else
      message="$1"
    fi
    ;;
  *)
    if [ -z "$base" ]; then
      base="$1"
    else
      echo 'Multiple bases specified' >&2
      usage
    fi
    ;;
  esac
  shift
done
if [ -z "$base" ]; then
  echo 'No base ref provided' >&2
  usage
fi

seq_ed="$(mktemp -t squash_edXXXXXX)" &&
  echo '#!'$(which bash)'
	echo Squashing... >&2
	tmp="$(mktemp -t squash_outXXXXXX)"
	awk '"'"'NR != 1 { sub(/^pick/, "squash") } {print}'"'"' "$1" > "$tmp"
	mv "$tmp" "$1"
' >$seq_ed &&
  chmod +x "$seq_ed" &&
  echo 'Warning: Forgetting local history. To revert, use:
  $ git reset --hard' $(git rev-parse --short HEAD) >&2
if [ -n "$message" ]; then
  GIT_SEQUENCE_EDITOR=$seq_ed GIT_EDITOR=touch git rebase -i $base
else
  GIT_SEQUENCE_EDITOR=$seq_ed git rebase -i $base
fi
if [ -n "$message" ]; then
  echo 'Updating commit message' >&2
  git commit --amend -m "$message" | head -n1
fi
rm -r "$seq_ed"