Quickly squash n git commits into the n+1th

squashtop.sh

#!/bin/bash

# Script to quickly squash the last n commits in your current git branch into the n+1th.
# The n+1th commit message is re-used, the others are discarded

# user input
COUNT="$1"

if [[ -z $COUNT ]] ; then
    printf "Usage: fixtop.sh [NUMBER]\nThis will squash the specified number of commits into the one right before.\n"
    printf "Example: \"fixtop.sh 3\" will squash the newest 3 commits into the fourth."
    exit 1
fi

# Find information from git
TARGET_SHA=$(git rev-parse HEAD~$(($COUNT)))
TARGET_MESSAGE=$(git show --pretty=format:%s -s $TARGET_SHA)
FIXED_MESSAGE=$(sed '1 s/"//gp' <<< "$TARGET_MESSAGE")

# Ask for user confirmation
COMMITS_TO_SQUASH=$(git log -$COUNT --oneline)
COMMIT_TO_SQUASH_INTO=$(git show --oneline -s $TARGET_SHA)
printf "\nDo you want to squash these commits:\n%s" "$COMMITS_TO_SQUASH"

printf "\ninto:\n%s" "$COMMIT_TO_SQUASH_INTO"

read -r -p "(y/n)"
echo
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
    echo "Aborted!"     
    exit 1
fi

# squash
git reset --soft HEAD~$COUNT && git commit -m "FIXED_MESSAGE"
echo "Done."