hadoop新手求教

root@boblee:/opt/hadoop-1.2.1# bin/hadoop version
Hadoop 1.2.1
Subversion https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2 -r 1503152
Compiled by mattf on Mon Jul 22 15:23:09 PDT 2013
From source with checksum 6923c86528809c4e7e6f493b6b413a9a
This command was run using /opt/hadoop-1.2.1/hadoop-core-1.2.1.jar
root@boblee:/opt/hadoop-1.2.1# hadoop
hadoop：未找到命令
root@boblee:/opt/hadoop-1.2.1# cd bin
root@boblee:/opt/hadoop-1.2.1/bin# hadoop fs -ls
hadoop：未找到命令
root@boblee:/opt/hadoop-1.2.1/bin# Hadoop dfs -ls
Hadoop：未找到命令
root@boblee:/opt/hadoop-1.2.1/bin# hadoop dfs -ls
hadoop：未找到命令
root@boblee:/opt/hadoop-1.2.1/bin# start-all.sh
start-all.sh：未找到命令
root@boblee:/opt/hadoop-1.2.1/bin#