linux安装配置JDK脚本

#!/bin/bash
# install jdk and configuring environment variables
function installjdk(){
tar -zxf jdk-8u201-linux-x64.tar.gz -C /usr/local
cat >> /etc/profile << EOF
export JAVA_HOME=/usr/local/jdk1.8.0_201
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
EOF
}

#-------------------------- testing jdk--------------------------
echo "========= Start to install JDK =============="
source /etc/profile
if [ -n "$JAVA_HOME" ];then
echo "JDK already installed"
java -version
else
if [ -f "./jdk-8u201-linux-x64.tar.gz" ];then
  installjdk
  source /etc/profile
  java -version
  echo "use the 'source /etc/profile' command to update local variables"
else
  echo "Missing 'jdk-8u201-linux-x64.tar.gz' file in statistical catalogue"
  echo "Failed to install JDK"
fi
fi
echo "========= End installation of JDK ==========="