hadoop命令

基本文件命令
hadoop fs -cmd<args>
cmd的命令通常与unix的命令相同，如 hadoop fs -ls

查看列表
hadoop fs -ls /

查看目录结构
hadoop fs -lsr /

创建目录(root 是当前用户的目录)
hadoop fs mkdir /user/root

加入文件
hadoop fs  put  example.txt  .
注意上面这个命令最后一个参数是(.)。这意味着我们把文件放入了默认的工作目录。
等价于
hadoop  fs  put  example.txt  /user/root/

删除
hadoop fs rm /user/root/example.txt //如果rm不行，用rmr

查看
hadoop fs -cat /user/root/example.txt
hadoop fs -cat hdfs://192.168.1.77:9002/user/root/example.txt

查看最后的一千个字节

hadoop fs  -tail  /user/root/example.txt

1.进入hadoop
/usr/mahout/hadoop-0.20.2/bin$hadoop 

 会出现hadoop命令格式以及hadoop有的命令结果如下：
Usage: hadoop [--config confdir] COMMAND
where COMMAND is one of:
  namenode-format    format the DFS filesystem
 secondarynamenode   run the DFS secondary namenode
 namenode            run the DFS namenode
 datanode            run a DFS datanode
 dfsadmin            run a DFS admin client
 mradmin             run a Map-Reduce admin client
 fsck                run a DFS filesystem checking utility
 fs                  run a generic filesystem user client
 balancer            run a cluster balancing utility
 jobtracker          run the MapReduce job Tracker node
 pipes               run a Pipes job
 tasktracker         run a MapReduce task Tracker node
 job                 manipulate MapReduce jobs
 queue               get information regarding JobQueues
 version             print the version
  jar           run a jar file
  distcp copy file or directoriesrecursively
  archive -archiveName NAME * create a hadooparchive
 daemonlog           get/set the log level for each daemon
 or
 CLASSNAME           run the class named CLASSNAME
Most commands print help when invoked w/o parameters.

获取到本地，注意上面这个命令最后一个参数是(.)
hadoop  fs  -get  /user/root/example.txt  .

查看帮助，如查看ls帮助
hadoop  fs  -help  ls