写入环境变量
$ cat>>/etc/bashrc<<EOF
JAVA_HOME=/packages/jdk1.8.0_201/
CLASSPATH=$JAVA_HOME/lib/
PATH=$PATH:$JAVA_HOME/bin
export PATH JAVA_HOME CLASSPATH
EOF
使环境变量生效
$ source /etc/bashrc
$ cat>>/etc/bashrc<<EOF
JAVA_HOME=/packages/jdk1.8.0_201/
CLASSPATH=$JAVA_HOME/lib/
PATH=$PATH:$JAVA_HOME/bin
export PATH JAVA_HOME CLASSPATH
EOF
$ source /etc/bashrc