keep_releases.sh

    releases_path=/data/sites/yoursite.com/releases # change this
    keep_releases=5

    versions=`ls -xt $releases_path`
    releases=(${versions// / })

    # check available number of versions in releases directory
    releases_count=${#releases[@]}

    if [ $releases_count -le $keep_releases ]
    then
      echo 'no old releases to clean up'
    else
      echo keeping $keep_releases of $releases_count deployed releases
      releases=(${releases[@]:0:0} ${releases[@]:($keep_releases)})

      for release in "${releases[@]}"
      do
        path=$releases_path$release
        `rm -rf $path`
      done
    fi