public void signal(ServiceType service, Signal signal, String hostname) throws IOException {
    execWithRetries(hostname, service,
      getCommandProvider(service).signalCommand(service, signal.toString()));
  }
Execute the given command on the host using SSH
@return pair of exit code and command output
@throws IOException if something goes wrong.
hbase-it/src/test/java/org/apache/hadoop/hbase/HBaseClusterManager.java