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The groovy native launcher is a native program for launching groovy scripts. It compiles to an executable binary file, e.g. groovy.exe on windows. Note that you still need to have groovy and jre or jdk installed, i.e. the native launcher is a native executable replacement for the startup scripts (groovy.bat,


The native launcher should support any platform and any jdk / jre (>= 1.4). If you find something that is not supported, please post a JIRA enhancement request and support will be added.

At the moment, the following platforms have been tested:

  • Windows (XP, Vista)
  • linux (SuSE, Ubuntu) on x86
  • solaris on sparc
  • OS-X

At the moment, the following jdks / jres have been tested

  • several versions of sun jre / jdk (from 1.4, 1.5 and 1.6 serieses)
  • jrockit (on windows)

Known issues

  • Paths are not converted on cygwin, so you have to use windows style paths when invoking scripts
  • On OS-X automatic detection of the executable location does not work. This means you have to set GROOVY_HOME


The binaries are compiled w/ the provided rant script. Just type

On Windows you can either compile w/ ms cl compiler + ms link from normal windows command prompt or gcc from cygwin or msys. On cygwin, you currently have to use the rant version from svn head, and run rant w/ the script rant/trunk/run_rant as the present rant release does not work w/ cygwin.


To use the native launcher, you need to either place the executable in the bin directory of groovy installation OR set the GROOVY_HOME environment variable to point to your groovy installation. If you do not use -jh / --javahome option, JAVA_HOME needs to be set also.

The launcher primarily tries to find the groovy installation by seeing whether it is sitting in the bin directory of one. If not, it resorts to using GROOVY_HOME environment variable. Note that this means that GROOVY_HOME environment variable does not need to be set to be able to run groovy.


The native launcher accepts accepts all the same parameters as the .bat / shell script launchers, and a few others on top of that. For details, type

groovy -h

JVM parameters

Any options not recognized as options to groovy are passed on to the jvm, so you can e.g. do

groovy -Xmx250m myscript.groovy

The -client (default) and -server options to designate the type of jvm to use are also supported, so you can do

groovy -Xmx250m -server myscript.groovy

Note that no aliases like -hotspot, -jrockit etc. are accepted - it's either -client or -server

You can freely mix jvm parameters and groovy parameters. E.g. in the following -d is param to groovy and -Dmy.prop=foo / -Xmx200m are params to the jvm:

groovy -Dmy.prop=foo -d -Xmx200m myscript.groovy


The environment variable JAVA_OPTS that the .bat/shell script launchers use is ignored.

groovy.exe and groovyw.exe on Windows

Similarly to java.exe and javaw.exe on a jdk, the build process produces groovy.exe and groovyw.exe on windows. The difference is the same as w/ java.exe and javaw.exe - groovy.exe requires a console and will launch one if it is not started in a console, whereas groovyw.exe has no console (and is usually used to start apps w/ their own gui or that run on the background).

Pre-compiled binaries

There are precompiled binaries for windows attached to this page (go to the bottom of the page, click "View" and then click on the "Attachments" tab). They are not guaranteed to be completely up to date with the sources in svn head, but they should work.
Hopefully we will have precompiled binaries for all supported platforms in the future.


Windows file association

If you want to run your groovy scripts on windows so that they seem like any other commands (i.e. if you have myscript.groovy on your PATH, you can just type myscript), do as follows:

  • add .groovy to PATHEXT environment variable
  • make changes in windows registry as follows
  • run regedit.exe
  • create a new key HKEY_CLASSES_ROOT\.groovy and give it the value groovyFile
  • create HKEY_CLASSES_ROOT\groovyFile
  • under that, create HKEY_CLASSES_ROOT\groovyFile\Shell and give it value open
  • under that, create HKEY_CLASSES_ROOT\groovyFile\Shell\open\command and give it value (adjust according to your groovy location) "c:\programs\groovy-1.0\bin\groovy.exe" "%1" %*

Yes, it would be nicer to have an installer do this. = )


Why have a native launcher, why aren't the startup scripts (groovy.bat, sufficient? Here are some reasons:

  • it solves an open bug : return value of groovy (on windows) is always 0 no matter what happens in the executed script ( even if you call System.exit(1) ). Granted, this could be solved by editing the launch scripts also.
  • it is slightly faster than the corresponding .bat / shell script
  • you can mix jvm params and groovy params, thus making it easier and more natural to e.g. reserve more memory for the started jvm.
  • the process will be called "groovy", not "java". Cosmetic, yes, but still nice. = )
  • fixes the problems there have been w/ the .bat launcher and paths w/ whitespace

Also, the launcher has been written so that the source can be used to easily create a native launcher for any Java program.

How it works

Essentially the launcher does the same thing that the normal java launcher (java executable) does - it dynamically loads the dynamic library containing the jvm and hands the execution over to it. It does not start a separate process (i.e. it does not call the java executable).

Help wanted

If you have expertise with any of the following and want to help, please email me at antti dot karanta (at) iki dot fi:

  • Cygwin c api
  • more specifically: how to successfully load and use the win <-> posix path conversion functions when loading the cygwin1.dll from a non-cygwin app
  • os-x c programming
  • more specifically: how to get the path to the current executable
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