在我的ubuntu 12.04.4上配置hadoop的方法如下：
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/
当我执行这个命令时

./hadoop dfs -mkdir /In

我有一个错误：

mkdir: org.apache.hadoop.security.AccessControlException: Permission denied: user=hduser, access=WRITE, inode="":root:supergroup:rwxr-xr-x

在如何执行命令中：

sudo chmod 750 /app/hadoop/tmp

如果我给chmod 777，错误就不会改变。我不明白问题是什么。
p、 s:how-to和我的配置之间的唯一区别是，在how-to中，hadoop-env.sh如下所示：

# The java implementation to use.  Required.

 export JAVA_HOME=/usr/lib/jvm/java-6-sun

在我的配置中，我有：

# The java implementation to use.  Required.

 export JAVA_HOME=/usr/lib/jvm/java-6-openjdk-amd64

因为我使用openjdk。
另一个问题是，如果我发出命令./start-all.sh，我有以下输出：

Warning: $HADOOP_HOME is deprecated.

 starting namenode, logging to /home/hduser/hadoop/libexec/../logs/hadoop-hduser-namenode-ubuntu.out
 hduser@localhost's password: 
 localhost: starting datanode, logging to /home/hduser/hadoop/libexec/../logs/hadoop-hduser-datanode-ubuntu.out
 hduser@localhost's password: 
 localhost: starting secondarynamenode, logging to /home/hduser/hadoop/libexec/../logs/hadoop-hduser-secondarynamenode-ubuntu.out
 starting jobtracker, logging to /home/hduser/hadoop/libexec/../logs/hadoop-hduser-jobtracker-ubuntu.out
 hduser@localhost's password: 
 localhost: starting tasktracker, logging to /home/hduser/hadoop/libexec/../logs/hadoop-hduser-tasktracker-ubuntu.out

我不明白他为什么问我好几次。
如果我执行command./stop all.s，我有以下输出：

Warning: $HADOOP_HOME is deprecated.

 no jobtracker to stop
 hduser@localhost's password: 
 localhost: stopping tasktracker
 no namenode to stop
 hduser@localhost's password: 
 localhost: no datanode to stop
 hduser@localhost's password: 
 localhost: no secondarynamenode to stop

正常吗？