Generate CHANGELOG.md from git tags

changelog.sh

#!/usr/bin/bash

# A bash script to generate a markdown changelog from git tags
# Run this inside a git repository to generate CHANGELOG.md file

if [ ! -d ".git" ]; then
  echo "Error: Not a git repository"
  exit 1
fi

OUTPUT=""

BEFORE=""
for tag in `git tag --list --sort=-version:refname`; do
  if [ ! -z "$BEFORE" ]; then
    OUTPUT+="# $tag ($(git log -1 --date=short --pretty=%ad $tag))\n"
    OUTPUT+=`git log $tag...$BEFORE --pretty="- %s"`
    OUTPUT+="\n\n"
  fi
  BEFORE=$tag
done

# Include the first tag too. (last in our list)
# This is because the loop above records BEFORE and tries next one
# When this tag comes, there's no next so it gets left behind.
OUTPUT+="# $BEFORE ($(git log -1 --date=short --pretty=%ad $BEFORE))\n"
OUTPUT+=`git log $BEFORE --pretty="- %s"`

echo -e "$OUTPUT"
echo -e "$OUTPUT" > CHANGELOG.md