git-squash.sh

#!/bin/bash
#
# Usage
#   git-squash.sh [-h|--help] [-E|--no-edit] NR
#
# Description
#   カレントディレクトリを含むリポジトリの HEAD コミットから過去
#   NR コミットを一つのコミットにまとめる。
#

show_help() {
	sed -n 2,$[$BASH_LINENO-4]p $BASH_SOURCE | grep "^#" | sed 's/^#/ /'
}

EDIT=true
while [[ $# -gt 0 ]] ; do
	key="$1"
	case $key in
		-h|--help)
			show_help
			exit 0
			;;
		-e|--edit)
			EDIT=true
			shift 1
			;;
		-E|--no-edit)
			EDIT=
			shift 1
			;;
		*) # end of options
			break
			;;
	esac
done

TSTAMP="`date +%y%m%d_%H%M%S`"
mkdir -p /tmp/$(basename $BASH_SOURCE)
TMPD=$(mktemp -d /tmp/$(basename $BASH_SOURCE)/${TSTAMP}.XXXXXX)

NR=$1

if [ ! "$NR" ] || ( ! [ "$NR" -gt 0 ] ) ; then
	echo "invalid argument" >&2
	show_help
	exit 1
elif [ "$NR" -eq 1 ] ; then
	echo "NR must be > 1" >&2
	exit 1
fi

if ! git diff --quiet ; then
	echo "Current working tree is dirty." >&2
	exit 1
fi

if [ "$EDIT" ] && [ ! "$EDITOR" ] ; then
	echo "You need set environment variable EDITOR to your favorite editor" >&2
	exit 1
fi

if [ "$(git log --oneline --merges HEAD~${NR} HEAD)" ] ; then
	echo "Given range includes merge commits, so you can't squash them" >&2
	exit 1
fi

git log --pretty="format:%B%n" -n ${NR} > $TMPD/description.txt

$EDITOR $TMPD/description.txt

git reset --soft HEAD~${NR} || exit 1
git commit -F $TMPD/description.txt || exit 1