[Bash]检查java版本信息

#!/bin/bash  
#set -x 
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 Java" 
fi  

if [[ "$_java" ]]; then 
    # version=$("$_java" -version 2>&1 | awk -F '"' '/version/ {print $2}') 
    #it will give you 16 for java like 1.6.0_13 and 15 for version like 1.5.0_17. 
    version=$(java -version 2>&1 | sed 's/java version "(.*).(.*)..*"/12/; 1q') 
    echo version "$version" 
    [ "$version" -ge 15 ] && echo "ok, java is 1.5 or newer" || echo "it's too old..." 
fi