generate a changelog from the git commit messages between the current branch and the most recent ancestor tag, or between two named refs

git-changelog2

#!/bin/bash

# gives a changelog from the most recent tag to the current HEAD, with blank lines removed

currentHead='HEAD'
lastTag=$(git describe --tags --abbrev=0 2>/dev/null)
if [ -z "${lastTag}" ]; then 
    fromType="initial commit"
    lastTag=$(git rev-list HEAD --max-parents=0 | cut -c 1-10)
fi

# if no args, $buildBranch..$currentBranch
# if one arg, $1..$currentBranch
# if twho args, $1..$2
fromBranch=${1-$lastTag}
toBranch=${2-$currentHead}

fromMsg="${fromType-$([ -z "${1}" ] && echo 'tag' || echo '')} ${fromBranch}"
echo "Change log from ${fromMsg} to ${toBranch}:"

git log "${fromBranch}..${toBranch}" --pretty='format:- %s (%aN) %n  %b' | grep '[^[:space:]]'