use ls instead of find to avoid incompatibility with gnu find

when i use gnu find (provided by homebrew findutils), an error is shown

```
find: warning: you have specified the -d option after a non-option argument -name, but options are not positional (-d affects tests specified before it as well as those specified after it).  Please specify options before other arguments.

find: warning: the -d option is deprecated; please use -depth instead, because the latter is a POSIX-compliant feature.
find: paths must precede expression: 1
Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]
```