Linux查看jdk安装路径
1. whereis java
2. which java
3. echo $JAVA_HOME
4. echo $PATH
5. echo $CLASSPATH
Linux设置环境变量vi /etc/profile
export JAVA_HOME=/usr/java/jdk1.8.0_121
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
source /etc/profile