which java
/usr/bin/java
ls -lrt /usr/bin/java
lrwxrwxrwx. 1 root root 22 3月 31 20:07 /usr/bin/java -> /etc/alternatives/java
ls -lrt /etc/alternatives/java
lrwxrwxrwx. 1 root root 71 3月 31 20:07 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.181-7.b13.el7.x86_64/jre/bin/java
cd /usr/lib/jvm/
OK