Java(tm) Binary Kernel Support for Linux v1.02 ---------------------------------------------- Linux beats them ALL! While all other OS's are TALKING about direct support of Java Binaries in the OS, Linux is doing it! You can execute Java applications and Java Applets just like any other program after you have done the following: 1) You MUST FIRST install the Java Developers Kit for Linux. The Java on Linux HOWTO gives the details on getting and installing this. This HOWTO can be found at: ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO You should also set up a reasonable CLASSPATH environment variable to use Java applications that make use of any nonstandard classes (not included in the same directory as the application itself). 2) You have to compile BINFMT_MISC either as a module or into the kernel (CONFIG_BINFMT_MISC) and set it up properly. If you choose to compile it as a module, you will have to insert it manually with modprobe/insmod, as kerneld can not easy be supported with binfmt_misc. Read the file 'binfmt_misc.txt' in this directory to know more about the configuration process. 3) Add the following configuration items to binfmt_misc (you should really have read binfmt_misc.txt now): support for Java applications: ':Java:M::\xca\xfe\xba\xbe::/usr/local/java/bin/javawrapper:' support for Java Applets: ':Applet:E::html::/usr/local/java/bin/appletviewer:' or the following, if you want to be more selective: ':Applet:M:: in the first line ('<' has to be the first character!) to let this work! For the compiled Java programs you need a wrapper script like the following (this is because Java is broken in case of the filename handling), again fix the path names, both in the script and in the above given configuration string: ====================== Cut here =================== #!/bin/bash # /usr/local/java/bin/javawrapper - the wrapper for binfmt_misc/java CLASS=$1 # if classname is a link, we follow it (this could be done easier - how?) if [ -L "$1" ] ; then CLASS=`ls --color=no -l $1 | tr -s '\t ' ' ' | cut -d ' ' -f 11` fi CLASSN=`basename $CLASS .class` CLASSP=`dirname $CLASS` FOO=$PATH PATH=$CLASSPATH if [ -z "`type -p -a $CLASSN.class`" ] ; then # class is not in CLASSPATH if [ -e "$CLASSP/$CLASSN.class" ] ; then # append dir of class to CLASSPATH if [ -z "${CLASSPATH}" ] ; then export CLASSPATH=$CLASSP else export CLASSPATH=$CLASSP:$CLASSPATH fi else # uh! now we would have to create a symbolic link - really # ugly, i.e. print a message that one has to change the setup echo "Hey! This is not a good setup to run $1 !" exit 1 fi fi PATH=$FOO shift /usr/local/java/bin/java $CLASSN "$@" ====================== Cut here =================== Now simply chmod +x the .class and/or .html files you want to execute. To add a Java program to your path best put a symbolic link to the main .class file into /usr/bin (or another place you like) omitting the .class extension. The directory containing the original .class file will be added to your CLASSPATH during execution. To test your new setup, enter in the following simple Java app, and name it "HelloWorld.java": class HelloWorld { public static void main(String args[]) { System.out.println("Hello World!"); } } Now compile the application with: javac HelloWorld.java Set the executable permissions of the binary file, with: chmod 755 HelloWorld.class And then execute it: ./HelloWorld.class To execute Java Applets, simple chmod the *.html files to include the execution bit, then just do ./Applet.html originally by Brian A. Lantz, brian@lantz.com heavily edited for binfmt_misc by Richard Günther.