安裝Hadoop:單機模式安裝Hadoop 安裝JAVA環境 設置環境變量，啓動運行

1.1 問題
本案例要求安裝單機模式Hadoop：

單機模式安裝Hadoop
安裝JAVA環境
設置環境變量，啓動運行
1.2 步驟
實現此案例需要按照如下步驟進行。

步驟一：環境準備

1）配置主機名爲nn01，ip爲192.168.1.60，配置yum源（系統源）

備註：由於在之前的案例中這些都已經做過，這裏不再重複，不會的學員可以參考之前的案例

2）安裝java環境

[root@nn01 ~]# yum -y install java-1.8.0-openjdk-devel
[root@nn01 ~]# java -version
openjdk version "1.8.0_131"
OpenJDK Runtime Environment (build 1.8.0_131-b12)
OpenJDK 64-Bit Server VM (build 25.131-b12, mixed mode)
[root@nn01 ~]# jps
1235 Jps

3）安裝hadoop

[root@nn01 ~]# cd hadoop/
[root@nn01 hadoop]# ls
hadoop-2.7.7.tar.gz  kafka_2.12-2.1.0.tgz  zookeeper-3.4.13.tar.gz
[root@nn01 hadoop]# tar -xf hadoop-2.7.7.tar.gz 
[root@nn01 hadoop]# mv hadoop-2.7.7 /usr/local/hadoop
[root@nn01 hadoop]# cd /usr/local/hadoop
[root@nn01 hadoop]# ls
bin  include  libexec      NOTICE.txt  sbin
etc  lib      LICENSE.txt  README.txt  share
[root@nn01 hadoop]# ./bin/hadoop   //報錯，JAVA_HOME沒有找到
Error: JAVA_HOME is not set and could not be found.
[root@nn01 hadoop]#

4）解決報錯問題

[root@nn01 hadoop]# rpm -ql java-1.8.0-openjdk
[root@nn01 hadoop]# cd ./etc/hadoop/
[root@nn01 hadoop]# vim hadoop-env.sh
25 export JAVA_HOME="/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64    /jre"
33 export HADOOP_CONF_DIR="/usr/local/hadoop/etc/hadoop"
[root@nn01 ~]# cd /usr/local/hadoop/
[root@nn01 hadoop]# ./bin/hadoop
Usage: hadoop [--config confdir] [COMMAND | CLASSNAME]
  CLASSNAME            run the class named CLASSNAME
 or
  where COMMAND is one of:
  fs                   run a generic filesystem user client
  version              print the version
  jar <jar>            run a jar file
                       note: please use "yarn jar" to launch
                             YARN applications, not this command.
  checknative [-a|-h]  check native hadoop and compression libraries availability
  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
  credential           interact with credential providers
                       Hadoop jar and the required libraries
  daemonlog            get/set the log level for each daemon
  trace                view and modify Hadoop tracing settings
Most commands print help when invoked w/o parameters.
[root@nn01 hadoop]# mkdir /usr/local/hadoop/input
[root@nn01 hadoop]# ls
bin  etc  include  lib  libexec  LICENSE.txt  NOTICE.txt  input  README.txt  sbin  share
[root@nn01 hadoop]# cp *.txt /usr/local/hadoop/input
[root@nn01 hadoop]# ./bin/hadoop jar  \
 share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.7.jar  wordcount input output        //wordcount爲參數 統計input這個文件夾，存到output這個文件裏面（這個文件不能存在，要是存在會報錯，是爲了防止數據覆蓋）
[root@nn01 hadoop]#  cat   output/part-r-00000    //查看