nixpkgs/pkgs/common-updater/scripts/list-git-tags

#!/usr/bin/env bash

# lists all available tags from a git repository

pname=""  # package name
attr_path="" # package attribute path
url="" # git repository url
file="" # file for writing debugging information

while (( $# > 0 )); do
    flag="$1"
    shift 1
    case "$flag" in
        --pname=*)
            pname="${flag#*=}"
            ;;
        --attr-path=*)
            attr_path="${flag#*=}"
            ;;
        --url=*)
            url="${flag#*=}"
            ;;
        --file=*)
            file="${flag#*=}"
            ;;
        *)
            echo "$0: unknown option ‘${flag}’"
            exit 1
            ;;
    esac
done

if [[ -z "$pname" ]]; then
    pname="$UPDATE_NIX_PNAME"
fi

if [[ -z "$attr_path" ]]; then
    attr_path="$UPDATE_NIX_ATTR_PATH"
fi

# By default we set url to src.url or src.meta.homepage
if [[ -z "$url" ]]; then
    url="$(nix-instantiate $systemArg --eval -E \
               "with import ./. {}; $attr_path.src.meta.homepage or $attr_path.src.url" \
        | tr -d '"')"
fi

# print a debugging message
if [[ -n "$file" ]]; then
    echo "# Listing tags for '$pname' at $url" >> $file
fi

# list all tags from the remote repository
tags=$(git ls-remote --tags --refs "$url")

# keep only the version part of the tag
tags=$(echo "$tags" | cut --delimiter=/ --field=3-)

echo "$tags"