Use alternatives for java version Conversion

Use alternatives to convert the java version-general Linux technology-Linux programming and kernel information. The following is a detailed description. After jdk was installed, java and javac were replaced with the java and javac of gij in/usr/bin.

Some people on the Internet said that they could use a tool named alternativs to migrate the software version in linux. They decided to use alternatives to migrate the jdk from gij to my newly installed jdk6.0.

Alternatives is in the/usr/sbin directory.

First, add the newly installed jdk to alternatives:

[Root @ djn-laptop sbin] #./alternatives -- install/usr/bin/java/usr/share/jdk1.6.0 _ 02/bin/java 300
[Root @ djn-laptop sbin] #./alternatives -- install/usr/bin/javac/usr/share/jdk1.6.0 _ 02/bin/javac 300

Then, use the -- display option to view the available JDK of the current system:

[Root @ djn-laptop sbin] #./alternatives -- display java
Java-the status is manual.
The link currently points to/usr/share/jdk1.6.0 _ 02/bin/java
/Usr/lib/jvm/jre-1.4.2-gcj/bin/java-1420 priority
From the keytool:/usr/lib/jvm/jre-1.4.2-gcj/bin/keytool
From rmiregistry:/usr/lib/jvm/jre-1.4.2-gcj/bin/rmiregistry
From jre_exports:/usr/lib/jvm-exports/jre-1.4.2-gcj
From jre:/usr/lib/jvm/jre-1.4.2-gcj
/Usr/share/jdk1.6.0 _ 02/bin/java-300 priority
From keytool :( null)
From rmiregistry :( null)
From jre_exports :( null)
From jre :( null)

Currently, the "best" version is/usr/lib/jvm/jre-1.4.2-gcj/bin/java.

[Root @ djn-laptop sbin] #./alternatives -- display javac
Javac-the status is manual.
The link currently points to/usr/share/jdk1.6.0 _ 02/bin/javac
/Usr/lib/jvm/java-1.4.2-gcj/bin/javac-1420 priority
Appletviewer:/usr/lib/jvm/java-1.4.2-gcj/bin/appletviewer
From jar:/usr/lib/jvm/java-1.4.2-gcj/bin/jar
From jarsigner:/usr/lib/jvm/java-1.4.2-gcj/bin/jarsigner
From javadoc:/usr/lib/jvm/java-1.4.2-gcj/bin/javadoc
From javah:/usr/lib/jvm/java-1.4.2-gcj/bin/javah
From rmic:/usr/lib/jvm/java-1.4.2-gcj/bin/rmic
From java_sdk_exports:/usr/lib/jvm-exports/java-1.4.2-gcj
From java_sdk:/usr/lib/jvm/java-1.4.2-gcj
/Usr/share/jdk1.6.0 _ 02/bin/javac-300 priority
From appletviewer :( null)
From jar :( null)
From jarsigner :( null)
From javadoc :( null)
From javah :( null)
From rmic :( null)
From java_sdk_exports :( null)
From java_sdk :( null)

The current "best" version is/usr/lib/jvm/java-1.4.2-gcj/bin/javac.

After confirmation, you can use the -- config parameter to select the JDK you want to use:

[Root @ djn-laptop sbin] #./alternatives -- config java

There are two programs that provide "java ".

Select command
-----------------------------------------------
* 1/usr/lib/jvm/jre-1.4.2-gcj/bin/java
+ 2/usr/share/jdk1.6.0 _ 02/bin/java

Press Enter to save the current selection [+], or type the selection Number:

[Root @ djn-laptop sbin] #./alternatives -- config javac

A total of two programs provide "javac ".

Select command
-----------------------------------------------
* 1/usr/lib/jvm/java-1.4.2-gcj/bin/javac
+ 2/usr/share/jdk1.6.0 _ 02/bin/javac

Press Enter to save the current selection [+], or type the selection Number:

Enter the JDK number. Of course, I chose the second option.