Java(tm) Binary Kernel Support for Linux v1.01
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Java(tm) Binary Kernel Support for Linux v1.01
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Linux beats them ALL! While all other OS's are TALKING about direct
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Linux beats them ALL! While all other OS's are TALKING about direct
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support of Java Binaries in the OS, Linux is doing it!
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support of Java Binaries in the OS, Linux is doing it!
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You execute Java classes as you would any other executable, after a few
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You execute Java classes as you would any other executable, after a few
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small details:
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small details:
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1) You MUST FIRST install the Java Developers Kit for Linux.
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1) You MUST FIRST install the Java Developers Kit for Linux.
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The Java on Linux HOWTO gives the details on getting and
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The Java on Linux HOWTO gives the details on getting and
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installing this. This HOWTO can be found at:
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installing this. This HOWTO can be found at:
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ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO
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ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO
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If you install the JDK in a location other than the suggested
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If you install the JDK in a location other than the suggested
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directory of /usr/local/java, then you will need to tell the
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directory of /usr/local/java, then you will need to tell the
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kernel where you put the Java interpreter.
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kernel where you put the Java interpreter.
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There are two ways to do this.
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There are two ways to do this.
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One, edit fs/binfmt_java.c file and make the needed change to
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One, edit fs/binfmt_java.c file and make the needed change to
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the _PATH_JAVA definition at the top of that file.
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the _PATH_JAVA definition at the top of that file.
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Two, as root, issue the command:
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Two, as root, issue the command:
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echo "/path/to/java/interpreter" > /proc/sys/kernel/java-interpreter
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echo "/path/to/java/interpreter" > /proc/sys/kernel/java-interpreter
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(Currently, this does not work if you're using a module for
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(Currently, this does not work if you're using a module for
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Java support.)
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Java support.)
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2) You must chmod the '*.class' files you wish to execute with
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2) You must chmod the '*.class' files you wish to execute with
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the execute bit. This is not normally (till now) done with
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the execute bit. This is not normally (till now) done with
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'.class' files.
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'.class' files.
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3) You must optionally export a CLASSPATH environment variable,
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3) You must optionally export a CLASSPATH environment variable,
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if you plan to use Java applications installed outside of
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if you plan to use Java applications installed outside of
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/usr/local/java/classes/*.
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/usr/local/java/classes/*.
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4) Either compile your kernel with Java support builtin, or
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4) Either compile your kernel with Java support builtin, or
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as a loadable module. If a module, load it with insmod or
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as a loadable module. If a module, load it with insmod or
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kerneld.
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kerneld.
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To test your new setup, enter in the following simple Java app, and name
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To test your new setup, enter in the following simple Java app, and name
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it "HelloWorld.java":
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it "HelloWorld.java":
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class HelloWorld {
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class HelloWorld {
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public static void main(String args[]) {
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public static void main(String args[]) {
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System.out.println("Hello World!");
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System.out.println("Hello World!");
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}
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}
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}
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}
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Now compile the application with:
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Now compile the application with:
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/usr/local/java/bin/javac HelloWorld.java
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/usr/local/java/bin/javac HelloWorld.java
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Set the executable permissions of the binary file, with:
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Set the executable permissions of the binary file, with:
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chmod 755 HelloWorld.class
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chmod 755 HelloWorld.class
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And then execute it:
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And then execute it:
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./HelloWorld.class
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./HelloWorld.class
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Yes, it's JUST THAT EASY! ;-)
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Yes, it's JUST THAT EASY! ;-)
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-----------------------------------------------------------------
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-----------------------------------------------------------------
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Nope, I didn't forget about Java Applets! ;-)
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Nope, I didn't forget about Java Applets! ;-)
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While this may not be the best way to do this, it works!
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While this may not be the best way to do this, it works!
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Take any html file used with the Java appletviewer (like the
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Take any html file used with the Java appletviewer (like the
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demo/Blink/example1.html file), and:
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demo/Blink/example1.html file), and:
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1) Insert a new first line of:
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1) Insert a new first line of:
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Make sure the '<' is the first character in the file. This
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Make sure the '<' is the first character in the file. This
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will be treated as a valid HTML comment outside of this
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will be treated as a valid HTML comment outside of this
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Java Applet support, so the modified file can still be used
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Java Applet support, so the modified file can still be used
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with all known browsers.
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with all known browsers.
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2) If you install the JDK in a location other than the suggested
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2) If you install the JDK in a location other than the suggested
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directory of /usr/local/java, then you will need to tell the
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directory of /usr/local/java, then you will need to tell the
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kernel where you put the Java appletviewer.
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kernel where you put the Java appletviewer.
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There are two ways to do this.
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There are two ways to do this.
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One, edit fs/binfmt_java.c file and make the needed change to
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One, edit fs/binfmt_java.c file and make the needed change to
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the _PATH_APPLET definition at the top of that file.
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the _PATH_APPLET definition at the top of that file.
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Two, as root, issue the command:
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Two, as root, issue the command:
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echo "/path/to/java/appletviewer" > /proc/sys/kernel/java-appletviewer
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echo "/path/to/java/appletviewer" > /proc/sys/kernel/java-appletviewer
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(Currently, this does not work if you're using a module for
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(Currently, this does not work if you're using a module for
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Java support.)
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Java support.)
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3) You must chmod the '*.html' files you wish to execute with
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3) You must chmod the '*.html' files you wish to execute with
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the execute bit. This is not normally (till now) done with
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the execute bit. This is not normally (till now) done with
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'.html' files.
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'.html' files.
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4) And then execute it.
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4) And then execute it.
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Brian A. Lantz
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Brian A. Lantz
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brian@lantz.com
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brian@lantz.com
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(/proc/sys/kernel/java-* support by Mike Shaver (shaver@ingenia.com))
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(/proc/sys/kernel/java-* support by Mike Shaver (shaver@ingenia.com))
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