This works as expected, printing the DOS help info:

  ruby -e 'print `help`'

but this does nothing:

  ruby -e 'print `echo "foo"`'

I'm using the latest ruby/win release, downloaded today, on Win2K.

The same thing happens within irb,.

Also, system behaves similarly:

system "help"
  ==> help info...

system "cd"
  ==> false