1：echo $JAVA_HOME

　　使用$JAVA_HOME的话能定位JDK的安装路径的前提是配置了环境变量$JAVA_HOME，否则如下所示，根本定位不到JDK的安装路径

　　[ ~]# java -version

　　java version 1.7.0_65

　　OpenJDK Runtime Environment (rhel-2.5.1.2.el6_5-x86_64 u65-b17)

　　OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode)

　　[ ~]# echo $JAVA_HOME

　　2：which java

　　首先要申明一下which java是定位不到安装路径的。which java定位到的是java程序的执行路径。网上的资料都是人云亦云，完全不去思考。那么怎么定位到java的安装路径呢?下面我们来看看例子吧,如下所示：

　　[ ~]# java -version

　　java version 1.7.0_65

　　OpenJDK Runtime Environment (rhel-2.5.1.2.el6_5-x86_64 u65-b17)

　　OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode)

　　[ ~]# which java

　　/usr/bin/java

　　[ ~]# ls -lrt /usr/bin/java

　　lrwxrwxrwx. 1 root root 22 Aug 17 15:12 /usr/bin/java -> /etc/alternatives/java

　　[ ~]# ls -lrt /etc/alternatives/java

　　lrwxrwxrwx. 1 root root 46 Aug 17 15:12 /etc/alternatives/java -> /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java

　　[ ~]#

　　[ ~]# cd /usr/lib/jvm

　　[ jvm]# ls

　　java-1.6.0-openjdk-1.6.0.0.x86_64 java-1.7.0-openjdk-1.7.0.65.x86_64 jre jre-1.6.0 jre-1.6.0-openjdk.x86_64 jre-1.7.0 jre-1.7.0-openjdk.x86_64 jre-openjdk

　　[ jvm]#

　　whereis java 也是如此，它本身不能定位到安装路径。可以通过上面例子去定位安装路径

　　3： rpm -ql packagename

　　如果JDK是源码安装的话，那么这个方法也是行不通的。也就是说rpm –ql packagename也是有一定局限性的。

　　[ ~]# java -version

　　java version 1.7.0_65

　　OpenJDK Runtime Environment (rhel-2.5.1.2.el6_5-x86_64 u65-b17)

　　OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode)

　　[ ~]# rpm -qa grep java

　　tzdata-java-2014g-1.el6.noarch

　　java-1.6.0-openjdk-1.6.0.0-11.1.13.4.el6.x86_64

　　java-1.7.0-openjdk-1.7.0.65-2.5.1.2.el6_5.x86_64

　　[ ~]# rpm -ql java-1.7.0-openjdk-1.7.0.65-2.5.1.2.el6_5.x86_64 more

　　/etc/.java

　　/etc/.java/.systemPrefs

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jaas-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jaas-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jaas.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jce-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jce-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jce.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jdbc-stdext-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jdbc-stdext-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jdbc-stdext-3.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jdbc-stdext.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-cos-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-cos-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-cos.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-ldap-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-ldap-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-ldap.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-rmi-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-rmi-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi-rmi.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jndi.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jsse-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jsse-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/jsse.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/sasl-1.7.0.65.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/sasl-1.7.0.jar

　　/usr/lib/jvm-exports/java-1.7.0-openjdk-1.7.0.65.x86_64/sasl.jar

　　/usr/lib/jvm-exports/jre-1.7.0-openjdk.x86_64

　　/usr/lib/jvm-private/java-1.7.0-openjdk.x86_64

　　/usr/lib/jvm-private/java-1.7.0-openjdk.x86_64/jce

　　/usr/lib/jvm-private/java-1.7.0-openjdk.x86_64/jce/vanilla

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/ASSEMBLY_EXCEPTION

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/LICENSE

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/THIRD_PARTY_README

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/java

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/keytool

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/orbd

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/pack200

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/policytool

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/rmid

　　/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64/jre/bin/rmiregistry

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