hdfs dfs -mkdir /tmp

WARN fs.filesystem failed to initialize file systemhdfs://dev-cluster:8020: 
java.lang.IllegalArgumentException: java.net.UnknownHostException: dev-cluster

CodePudding user response：

The error is saying you have no host known to the DNS server setup by your client that's named dev-cluster.

If you're trying to use an HDFS nameservice, then you've not fully configured the hdfs-site.xml for the command to use a nameservice