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 <jar>            run a jar file
distcp <srcurl> <desturl> copy file or directories recursively
archive -archiveName NAME -p <parent path> <src>* <dest> 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 <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。