linux jdk静默安装

#下载&解压

mkdir /opt/java/
cd  /opt/java/
wget  http://download.oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.tar.gz
tar xvf jdk-7u79-linux-x64.tar.gz

1.经过软链接

ln -s   /opt/java/jdk1.7.0_79/bin/java /usr/bin/java
ln -s   /opt/java/jdk1.7.0_79/bin/javac /usr/bin/javac
--去掉软链接 rm /usr/bin/java

2.经过配置 /etc/profile 对全部用户有效

vi /etc/profile
JAVA_HOME=/opt/java/jdk1.7.0_79/
PATH=$JAVA_HOME/bin:$PATH
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME
export PATH
export CLASSPATH

3.修改~/.bashrc文件（该方法修改后只对当前用户有效，对该用户的全部shell都有效）

vi  ~/.bashrc
JAVA_HOME=/opt/java/jdk1.7.0_79/
PATH=$JAVA_HOME/bin:$PATH
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME
export PATH
export CLASSPATH