¿Cómo cambio lo que devuelve / usr / libexec / java_home?

$ echo $JAVA_HOME 
/Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home
$ /usr/libexec/java_home --verbose
Matching Java Virtual Machines (2):
   1.6.0_65-b14-468, x86_64:    "Java SE 6" /Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
   1.6.0_65-b14-468, i386:  "Java SE 6" /Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

$ ls /Library/Java/JavaVirtualMachines
1.6.0.jdk/
jdk1.7.0_17.jdk/
jdk1.7.0_71.jdk/
jdk1.7.0_80.jdk/
jdk1.8@ -> jdk1.8.0_66.jdk
jdk1.8.0_66.jdk/

¿Cómo obtengo / usr / libexec / java_home para devolver mis máquinas virtuales Java 1.8?