PHP生成linux命令行进度条

<?php
$total = 100;
for ($i = 1; $i <= $total; $i++) {
  printf("progress: [%-50s] %d%% Done
", str_repeat('#',$i/$total*50), $i/$total*100);
  sleep(1);
}
echo "
";
echo "Done!
";

在命令行执行比较长时间的任务时，需要实时查看进度。所以需要显示进度条