curl http://localhost:9200/_cluster/settings?pretty=true
{
"persistent" : {
"cluster" : {
"max_shards_per_node" : "xxxx"
}
},
"transient" : { }
}

curl -XPUT http://localhost:9200/_cluster/settings -H "Content-Type: application/json" -d '{ "persistent": { "cluster.max_shards_per_node": "xxxx" } }'