【Centos7】卸载OpenJDK

一般情况下，centos会自带OpenJDK，Hadoop的运行环境要求自己配置JRE，但在home下配置好了JRE后，使用java -version仍然看到OpenJDK，原因是系统根据$PATH路径，首先会在/usr/bin/中找到OpenJDK的java，并非我们自己配置的JDK。

解决办法有两种：1.配置/etc/profile使/home/xxx/jdk/bin首先被找到。2.卸载OpenJDK

这里推荐第二种

1.查看安装了哪些OpenJDK

sudo rpm -qa | grep jdk

2.卸载OpenJDK

sudo yum -y remove java-1.8.0-open*

3.这时在/usr/bin中已经没有java了

4.使用java -version看到了自己配置的JDK，这里已经成功卸载

[hadoop@master1 ~]$ java -version
java version "1.8.0_111"
Java(TM) SE Runtime Environment (build 1.8.0_111-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.111-b14, mixed mode)

5.这一步可以不看了，仅仅是通过卸载记录来研究OpenJDK的RPM包依赖关系

[oracle@hadoop ~]$ yum -y remove java-1.8.0-openjdk*
Loaded plugins: fastestmirror
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
You need to be root to perform this command.
[oracle@hadoop ~]$ su
Password: 
[root@hadoop oracle]# yum -y remove java-1.8.0-openjdk*
Loaded plugins: fastestmirror
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
Resolving Dependencies
--> Running transaction check
---> Package java-1.8.0-openjdk-headless.x86_64 1:1.8.0.111-2.b15.el7_3 will be erased
--> Processing Dependency: java-headless >= 1:1.6 for package: 1:libreoffice-core-5.0.6.2-3.el7.x86_64
---> Package unoconv.noarch 0:0.6-7.el7 will be erased
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
 Package                      Arch    Version                   Repository
                                                                           Size
================================================================================
Removing:
 java-1.8.0-openjdk-headless  x86_64  1:1.8.0.111-2.b15.el7_3   @updates  102 M
Removing for dependencies:
 libreoffice-calc             x86_64  1:5.0.6.2-3.el7           @base      29 M
 unoconv                      noarch  0.6-7.el7                 @base     196 k

Transaction Summary
================================================================================
Remove  1 Package (+10 Dependent packages)

Installed size: 402 M
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Erasing    : unoconv-0.6-7.el7.noarch                                    1/11 
  Erasing    : 1:java-1.8.0-openjdk-headless-1.8.0.111-2.b15.el7_3.x86_   11/11 
failed to read link /usr/bin/java: No such file or directory
  Verifying  : 1:libreoffice-writer-5.0.6.2-3.el7.x86_64                   1/11 
  Verifying  : 1:libreoffice-impress-5.0.6.2-3.el7.x86_64                  2/11 
  Verifying  : 1:libreoffice-pdfimport-5.0.6.2-3.el7.x86_64                3/11 
Removed:
  java-1.8.0-openjdk-headless.x86_64 1:1.8.0.111-2.b15.el7_3                    
Dependency Removed:
  libreoffice-calc.x86_64 1:5.0.6.2-3.el7                                                                          
  unoconv.noarch 0:0.6-7.el7                                                    

Complete!
[root@hadoop oracle]# 

通过记录可以看出 libreoffice这个软件是基于JAVA的，卸载OpenJDK后，libreoffice就不能用了，节省了402M的磁盘空间。