We know root directory is /, and according to posix, there is another directory // which differs from /. When you ls / and ls //, the output is the same, so as stat, however if you cd / and cd //, they are different, though the directory content are the same. That really confused me. Anyone got an answer?
From Bash FAQ:
E10) Why does `cd //' leave $PWD as `//'?
POSIX.2, in its description of `cd', says that *three* or more leading
slashes may be replaced with a single slash when canonicalizing the
current working directory.
This is, I presume, for historical compatibility. Certain versions of
Unix, and early network file systems, used paths of the form
//hostname/path to access `path' on server `hostname'.
来源：https://stackoverflow.com/questions/16840916/what-is-path-how-is-it-different-from