On 16/08/2008, ara.t.howard <ara.t.howard / gmail.com> wrote:
>
>  On Aug 16, 2008, at 7:13 AM, Thomas Bl. wrote:
>
>
> > Hello.
> >
> > I have two problems.
> >
> > First: is there an easy way to redirect data from an incoming IO stream
> > to an outgoing IO stream, in a nonblocking way? For example, can you run
> > a console program from Ruby program and redirect the program's output to
> > STDOUT in realtime? I know one solution that works, but is there
> > anything better?
> >
> > Thread::new(IO::popen(COMMAND))\
> > { |srv|
> >  until srv.eof?
> >   print srv.readpartial(1024)
> >  end
> > }
> >
> > Replacing readpartial with sysread also works, and with read_nonblock
> > works partially.
> >
> > Second problem: when I use the code above, and at the same time the main
> > thread is waiting on Process.waitpid for some other program (not the one
> > of which I redirect the output, but some else), then the waiting doesn't
> > terminate correctly. It waits until the process finishes, and then,
> > until there is some data available from the process I'm streaming in the
> > thread above. And only then the main thread goes on.
> >
> > I use Windows XP, Ruby 1.8.6.
> >
> > Here's a blog entry describing the same problem, with no solution:
> > http://al2o3-cr.blogspot.com/2008/08/iopopen.html .
> >
>
>
>  you can do it, but not on windows.
>

If Ruby on Windows emulates fork (and there is nothing in the docs
saying fork would not work on some platforms) you can use fork and
execute the program normally without popen. The program then inherits
the standard output fd and you do not have to copy the data to it.

For copying data I haven't found a working solution on Linux either.

Thanks

Michal