code: public void create(@Nonnull QEmuImageFormat format, @Nonnull File backingFile) throws IOException {
          ProcessBuilder builder = new ProcessBuilder("qemu-img", "create", "-f", format.name(), "-b", backingFile.getPath(), file.getAbsolutePath());
          Process process = builder.start();
          ByteStreams.copy(process.getInputStream(), System.err);
      }
docs: Creates this image.
  <p>
  The size of the new image is derived from the existing backing file.
  <p>
  backingFile is referenced by a relative path. If you want it referenced
  absolutely, canonicalize the argument with {@link File#getAbsoluteFile()}
  before calling this method.
  
  @param format      The image format for the new image.
  @param backingFile The backing file for the new image.