java centos7配置查看jdk环境变量

[root@bogon java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64]# which java
/usr/bin/java
[root@bogon java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64]# ls -lrt /usr/bin/java
lrwxrwxrwx. 1 root root 22 4月 30 01:07 /usr/bin/java -> /etc/alternatives/java
[root@bogon java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64]# ls -lrt /etc/alternatives/java
lrwxrwxrwx. 1 root root 73 4月 30 01:07 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64/jre/bin/java
[root@bogon java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64]#

至此断定jdk安装路径为：/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64

vi   /etc/profile

在最后面加上：

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64
export PATH=$JAVA_HOME/bin:$PATH

export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

保存退出

source /etc/profile

验证：

echo $JAVA_HOME

[root@bogon java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64]# echo $JAVA_HOME
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64