如何使用Bash Shell检查Java版本？

看看我的整个脚本 https://github.com/darshanpatidar1/Environment-Setup/blob/master/version.sh， 用于检查Java，Python和其他版本

#!/bin/bash
#echo "Checking java JDK version"
#command -v javac >/dev/null 2>&1 || { echo >&2 "Java JDK is not installed"; }
#variables
        purge_='sudo apt-get purge '
        update_='sudo apt update '
        install_='sudo apt install ' 

#checking for java files and exe
echo Java JRE -
if type -p java; then
    echo Found Java executable in PATH
    _java=java  
elif [[ -n $JAVA_HOME ]] && [[ -x "$JAVA_HOME/bin/java" ]];  then
    echo Found Java executable in JAVA_HOME
    _java="$JAVA_HOME/bin/java"
else
    echo "no JRE found"
fi

if [[ "$_java" ]]; then
    version=$("$_java" -version 2>&1 | awk -F '"' '/version/ {print $2}')
    echo Version "$version"
fi

echo
echo Java JDK -
if type -p javac; then
    echo Found Javac executable in PATH
    _javac=javac  
elif [[ -n $JAVA_HOME ]] && [[ -x "$JAVA_HOME/bin/javac" ]];  then
    echo Found Javac executable in JAVA_HOME
    _javac="$JAVA_HOME/bin/javac"
else
    echo "no JDK found"
    echo "Previous Java JDK files will also be removed in installation."
    read -r -p "Do you want to install it now? [y/N] " response
    if [[ "$response" =~ ^([yY][eE][sS]|[yY])+$ ]]
    then
            echo "Installing Java JDK "
        $purge_ 'java openjdk-*'
        $update_
        $install_ java -y
    else
           echo "Installation aborted !"
           exit
    fi
fi

if [[ "$_javac" ]]; then
    version=$("$_javac" -version 2>&1   | awk '{print $2}')
    echo Version "$version"
fi
#javac -version 2>&1 | head -n 1
#end of java