1. 运用 `test` 指令（`; then echo Directory existselse echo Directory does not existfi```
2. 运用 `bash` 的 `d` 选项:```bashif ; then echo Directory existselse echo Directory does not existfi```
3. 运用 `bash` 的 `qwe2; then echo Directory existselse echo Directory does not existfi```
4. 运用 `find` 指令:```bashif find /path/to/directory > /dev/null 2>
