hadoop命令和目录

一 命令概述：

(1)hadoop下的显示：

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
  fetchdt              fetch a delegation token from the NameNode
  jobtracker           run the MapReduce job Tracker node
  pipes                run a Pipes job
  tasktracker          run a MapReduce task Tracker node
  historyserver        run job history servers as a standalone daemon
  job                  manipulate MapReduce jobs
  queue                get information regarding JobQueues
  version              print the version
  jar             run a jar file
  distcp   copy file or directories recursively
  archive -archiveName NAME -p  *  create a hadoop archive
  classpath            prints the class path needed to get the
                       Hadoop jar and the required libraries
  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.

二 编译和运行：

(1) 编译：

*javac -classpath ${HADOOP_VERSION}-core.jar wordcount/*

*${HADOOP_VERSION}-core.jar 在hadoop安装目录下，是Hadoop代码编译后的jar包。

(2) 运行：

*hadoop jar [mainClass] args...

*例如：hadoop jar wordcount.jar 包名.wordcount input output

三 Hadoop目录(常用)：

(1)src：hadoop源代码。

*core：基础代码库。

*hdfs：HDFS实现代码。

*mapred：MapReduce实现代码。

*tools：Hadoop工具，比如日志分析等。

*C++：c++代码，如pipes等。

(2)conf：各种配置文件。

(3)lib：运行时依赖的第三方库。

(4)bin：Hadoop管理脚本。

(5)hadoop-core-xxx.jar：Hadoop代码编译后的jar包。