The process exit stuff should be fixed for sure though.

Definitely not, I just wanted to point out that it behaves a little different than mri. I think this should be documented somewhere, but I don't know what a proper place would be. Is there a document on the differences between mri and jruby? I know, in an ideal world, we'd have no need for such document...

http://headius.com/jrubywiki/index.php/Differences_between_mri_and_jruby

It is linked to from the main wiki page. Now the page contains this process launching thing and missing continuations, but I guess there will be more.

The following program gives a better idea of why things go for (I just use Python to generate the exit code ):

puts system('python -c "import sys; sys.exit(2)"')
puts $?
puts $?>>8

CRuby on Windows and Linux prints:

false
512
2

JRuby on Windows and Linux prints:

false
2
0

The value put into $? is the return value of waitFor() called on a Process returned from ShellLauncher.run(IRubyObject[]). This Process can either be a ScriptThreadProcess or whatever is returned by Runtime.getRuntime().exec(...). From the OpenJDK sources I can see that this is a java.lang.ProcessImpl on Windows and a java.lang.UNIXProcess on Solaris and Linux.

On Windows, ProcessImpl's waitFor ends up calling the Win32 API function GetExitCodeProcess. On Solaris/Linux, they do all kinds of interesting things with the return value of waitpid, depending on whether the exit code indicates that the process was terminated by a signal.

In conclusion, it looks like some shifting and/or other mangling of the exit code needs to be done by JRuby before it puts it into $? (at least when using Java's Process implementation; not sure what has to happen for ScriptThreadProcess).

#!/usr/bin/env python
import os
import signal
os.kill(os.getpid(), signal.SIGHUP)

JRuby:

[albert@dogbert ~]$ jruby -e 'system("./signal.py"); puts $?'
129

MRI:

[albert@dogbert ~]$ ruby -e 'system("./signal.py"); puts $?'
1

SIGHUP is signal number 1.

I could be wrong, but it looks like JRuby is also missing a few Process::Status pieces like signaled? and stopsig.

C:\programs\jruby>ruby -e "system('ruby -e \"exit(2)\"');print $?>>8"
2
C:\programs\jruby>jruby -e "system('ruby -e \"exit(2)\"');print $?>>8"
\"');print $?>>8") was unexpected at this time.

Since it works w/ mri (the first line) I don't think it's a win command prompt issue.