Bash script to generate a changelog

generate-changelog.sh

#!/usr/bin/env bash
# Generates a changelog between tagged releases. Collects commits of pull requests, major, and bugfix tags

repository_url="https://bitbucket.org/MYPROJECT/MYREPO"

function generate_changelog() {
    previous_tag=0
    for current_tag in $(git tag --sort=-creatordate)
    do
        if [ "$previous_tag" != 0 ];then
            tag_date=$(git log -1 --pretty=format:'%ad' --date=short ${previous_tag})
            printf "## ${previous_tag} (${tag_date})\n\n"
            git log ${current_tag}...${previous_tag} --pretty=format:"* %s [View](${repository_url}/commits/%H)" | grep -E "pull request|major|bugfix"
            printf "\n\n"
        fi
        previous_tag=${current_tag}
    done

    # Show initial release for first tag
    tag_date=$(git log -1 --pretty=format:'%ad' --date=short ${current_tag})
    printf "## ${current_tag} (${tag_date})\n\n"
    printf "* Initial release"
}

generate_changelog > CHANGELOG.md