bin/pacprune

#!/usr/bin/env bash
#
# pbrisbin 2013 - list packages for which more than N versions exist in
# the current directory.
#
###
versions_to_keep=${1:-3}

parse() {
  local package opt

  while read -r package; do
    case "$package" in
      *gz) opt='-qxzf' ;;
      *xz) opt='-qxJf' ;;
    esac

    bsdtar -O $opt "$package" .PKGINFO |\
      awk -v pkg="$package" '/^pkgname/ { printf("%s %s\n", $3, pkg) }'
  done
}

prune() {
  local name package last_seen='' num_seen=0

  while read -r name package; do
    [[ "${last_seen:-$name}" != "$name" ]] && num_seen=0

    (( ++num_seen > versions_to_keep )) && readlink -f "$package"

    last_seen="$name"
  done
}

find ./ -maxdepth 1 -type f -name '*.pkg.tar.[gx]z' |\
  LC_ALL='C' sort -rV | parse | prune