1.1. help

$  etcdctl defrag --help
NAME:
        defrag - Defragments the storage of the etcd members with given endpoints

USAGE:
        etcdctl defrag [flags]

OPTIONS:
      --cluster[=false] use all endpoints from the cluster member list
      --data-dir=""     Optional. If present, defragments a data directory not in use by etcd.
  -h, --help[=false]    help for defrag