Last login: Sat Nov  1 13:13:59 on ttys000
GengdeMacBook-Air:~ geng$ ls
Desktop                Downloads        Library                Music                Public
Documents        Dropbox                Movies                Pictures
GengdeMacBook-Air:~ geng$ cd desktop
GengdeMacBook-Air:desktop geng$ cd xin
GengdeMacBook-Air:xin geng$ ls -l
total 0
drwxr-xr-x  3 geng  staff  102 11  1 13:22 23
GengdeMacBook-Air:xin geng$ cd 23
GengdeMacBook-Air:23 geng$ pwd
/Users/geng/desktop/xin/23
GengdeMacBook-Air:23 geng$ cd xin
-bash: cd: xin: No such file or directory
GengdeMacBook-Air:23 geng$
最后的这两行 我要是想退到上一个文件需要输入什么指令

让各位见笑了 cd ../  找到了

cd .. 还回上一级目录