how to check hdfs

[Shengdi Jin]

Hi all,
I just start to learn hadoop, I have a naive question

I used
    hdfs dfs -ls /home/cluster
to check the content inside.
But I get error
    ls: No FileSystem for scheme: hdfs

My configuration file core-site.xml is like
<configuration>
<property>
  <name>fs.defaultFS</name>
  <value>hdfs://master:9000</value>
</property>
</configuration>

hdfs-site.xml is like
<configuration>
<property>
   <name>dfs.replication</name>
   <value>2</value>
</property>
<property>
   <name>dfs.name.dir</name>
   <value>file:/home/cluster/mydata/hdfs/namenode</value>
</property>
<property>
   <name>dfs.data.dir</name>
   <value>file:/home/cluster/mydata/hdfs/datanode</value>
</property>
</configuration>

is there any thing wrong ?

Thanks a lot.