realpath -m //sysname/rootdir/.
returns "/sysname/rootdir" This is incorrect, according to POSIX.
and #3-4 have specific meanings in various applications that in usage.
1) leading double slashes are to be preserved
My Notes: in combining paths like pathcat(//, sys, /a) =>
should get //sys/a
in combining paths like pathcat(//, /sys, /a) => /sys sys
specifies it wants to be directory, not a system., so at root, '//' refer to
no system, and we just get: '/sys/a'
2) final slash indicates end node is a directory
3) a final . in a source specifies something under the directory name.
~4?) I don't think /.. at end of a pathname can be safely deleted
and have same meaning as without it, but brain is too tired to detail
right now.
