}else{
      zExternalCommand = db_get("gdiff-command", 0);
    }
    if( zExternalCommand==0 ){
      internalDiff=1;
    }
    blob_zero(&cmd);
    shell_escape(&cmd, zExternalCommand);
    blob_append(&cmd, " ", 1);
  }
  zFile = g.argv[g.argc-1];
  file_tree_name(zFile, &fname, 1);

  blob_zero(&vname);
  do{
    blob_reset(&vname);

    blob_reset(&out);
  }else{
    blob_write_to_file(&record, blob_str(&vname));
    blob_reset(&record);
    shell_escape(&cmd, blob_str(&vname));
    blob_appendf(&cmd, " ");
    shell_escape(&cmd, zFile);
    portable_system(blob_str(&cmd));
    unlink(blob_str(&vname));
    blob_reset(&vname);
    blob_reset(&cmd);
  }
  blob_reset(&fname);
}

/*
** This function implements a cross-platform "system()" interface.
*/
void portable_system(char *zOrigCmd){
#ifdef __MINGW32__
  /* On windows, we have to put double-quotes around the entire command.
  ** Who knows why - this is just the way windows works.
  */
  char *zNewCmd = mprintf("\"%s\"", zOrigCmd);
  system(zNewCmd);
  free(zNewCmd);
#else
  /* On unix, evaluate the command directly.
  */
  system(zOrigCmd);
#endif  
}