Florin Iucha wrote: > The -X flags are private and specific to Sun/IBM/etc.. I would expect > -jar to be supported though. The Sun JVM documentation is here http://java.sun.com/j2se/1.5.0/docs/tooldocs/solaris/java.html The gcj documentation is here http://gcc.gnu.org/onlinedocs/gcj/Invoking-gcj.html#Invoking-gcj The original command line is here: % java -Xmx256m -jar FileIndexer-1.1.5.jar I haven't found how to perform basic heap tuning (-Xmx256m) with gcj executables, but this shouldn't be necessary (only a performance improvement). One *ought* to simulate the workings of -jar by finding the main class in the jar manifest: % main=`unzip -c FileIndexer-1.1.5.jar META-INF/MANIFEST.MF | gawk '/^Main-Class:/ { print $2}'` Then you should be able to run gcj like this % gcj --main=$main Then run the executable (if gcj compiles w/o errors) as: % ./FileIndexer But, of course, I would advocate the performance advantages of dynamic compilation and point you to the Sun JVM ;-) Regards, --Tom P.S. FWIW setting CLASSPATH is deprecated in favor of using -cp (with the Sun JVM)