1、查看系統版本及當前java環境
[root@linuxprobe home]# cat /etc/system-release ## 查看系統版本 Red Hat Enterprise Linux release 8.0 (Ootpa) [root@linuxprobe home]# java ##檢測是否安裝java bash: java: command not found... Failed to search for file: Cannot update read-only repo [root@linuxprobe home]# java -version ## 查看版本 bash: java: command not found... Failed to search for file: Cannot update read-only repo [root@linuxprobe home]# which java ## 是否有java執行命令 /usr/bin/which: no java in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin) [root@linuxprobe home]# uname -a ## 查看系統內核、架構 Linux linuxprobe.com 4.18.0-80.el8.x86_64 #1 SMP Wed Mar 13 12:02:46 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux [root@linuxprobe home]# hostnamectl ## 同上 Static hostname: linuxprobe.com Icon name: computer-vm Chassis: vm Machine ID: 1667052376ea4207aa566e9d7a42456b Boot ID: c37ae01cf99e40909900fa77495cca76 Virtualization: vmware Operating System: Red Hat Enterprise Linux 8.0 (Ootpa) CPE OS Name: cpe:/o:redhat:enterprise_linux:8.0:GA Kernel: Linux 4.18.0-80.el8.x86_64 Architecture: x86-64
2、下載最新java安裝包 、安裝
下載地址：https://www.oracle.com/java/technologies/javase-jdk15-downloads.html
下載至：/home/software （可選）
[root@linuxprobe software]# ll -h total 180M -rw-r--r--. 1 root root 180M Oct 17 01:30 jdk-15_linux-x64_bin.tar.gz [root@linuxprobe software]# pwd /home/software [root@linuxprobe software]# tar -xzvf jdk-15_linux-x64_bin.tar.gz ## 解壓 [root@linuxprobe software]# mv jdk-15_linux-x64_bin.tar.gz jdk-15 ## 將安裝包移動至解壓的文件夾 [root@linuxprobe software]# mv jdk-15/ java ## 對文件夾進行重命名
[root@linuxprobe software]# cd java/bin/ ## 進入java程序的路徑
[root@linuxprobe bin]# ls
jaotc java javap jdb jfr jinfo jmod jrunscript jstat rmid
jar javac jcmd jdeprscan jhsdb jlink jpackage jshell jstatd rmiregistry
jarsigner javadoc jconsole jdeps jimage jmap jps jstack keytool serialver
[root@linuxprobe bin]# pwd ##輸出當前路徑
/home/software/java/bin
[root@linuxprobe bin]# echo $PATH ## 顯示路徑環境變量
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin
[root@linuxprobe bin]# ln -s /home/software/java/bin/java /usr/bin/java ## 在/usr/bin路徑下建立java可執行程序的軟鏈接，注意建立軟鏈接一定要使用絕對路徑
3、測試安裝結果
[root@linuxprobe bin]# java ## 可以執行 Usage: java [options] <mainclass> [args...] (to execute a class) or java [options] -jar <jarfile> [args...] (to execute a jar file) or java [options] -m <module>[/<mainclass>] [args...] java [options] --module <module>[/<mainclass>] [args...] (to execute the main class in a module) [root@linuxprobe bin]# java -version ## 查看版本 java version "15" 2020-09-15 Java(TM) SE Runtime Environment (build 15+36-1562) Java HotSpot(TM) 64-Bit Server VM (build 15+36-1562, mixed mode, sharing) [root@linuxprobe bin]# which java ## 查看可執行程序 /usr/bin/java
[root@linuxprobe bin]# whoami root [root@linuxprobe bin]# su - linuxprobe ## 切換至普通用戶檢測，沒有問題 [linuxprobe@linuxprobe ~]$ whoami linuxprobe [linuxprobe@linuxprobe ~]$ java Usage: java [options] <mainclass> [args...] (to execute a class) or java [options] -jar <jarfile> [args...] (to execute a jar file) or java [options] -m <module>[/<mainclass>] [args...] java [options] --module <module>[/<mainclass>] [args...] (to execute the main class in a module) [linuxprobe@linuxprobe ~]$ java -version java version "15" 2020-09-15 Java(TM) SE Runtime Environment (build 15+36-1562) Java HotSpot(TM) 64-Bit Server VM (build 15+36-1562, mixed mode, sharing) [linuxprobe@linuxprobe ~]$ which java /usr/bin/java
4、卸載：刪除建立的軟鏈接、刪除java的安裝包
[linuxprobe@linuxprobe ~]$ su - root ## 切換至root
Password:
[root@linuxprobe ~]# whoami
root
[root@linuxprobe ~]# rm -rf /usr/bin/java ## 刪除軟鏈接 [root@linuxprobe ~]# rm -rf /home/software/java ## 刪除安裝包 [root@linuxprobe ~]# java ## 檢測卸載效果 bash: java: command not found... Failed to search for file: Cannot update read-only repo [root@linuxprobe ~]# java -version ##同上 bash: java: command not found... Failed to search for file: Cannot update read-only repo [root@linuxprobe ~]# which java ##同上 /usr/bin/which: no java in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin)