On Apr 8, 2005 4:43 PM, Jason Zheng <xin.zheng@xxxxxxxxxxxx> wrote: > Manu Jose wrote: > > >Hi Jason, > > "." represents the current working directory and ".." > >represents the parent directory of the current working directory . It > >is useful in various contexts. For example if u r currently in the > >directory /mnt/foo and want to copy the content of /mnt/foo1 to > >/mnt/foo just isuue the command " cp -R /mnt/foo1/* . " .So it is > >always good to represent the working directory with a short symbol and > >it is not at all a waste.... > > > >Manu > > > >-- > >Kernelnewbies: Help each other learn about the Linux kernel. > >Archive: http://mail.nl.linux.org/kernelnewbies/ > >FAQ: http://kernelnewbies.org/faq/ > > > > > > > > > Let me rephrase my question a little bit: BESIDES the obvious usage of > "." entry, in terms of the filesystem, what is the purpose of "." entry? > > The obvious answer is that you can refer to the current directory using > "./", however, in order to look up the "." entry, the kernel must have a > knowledge of the current directory in the first place, doesn't it? The > kernel needs the directory table for the current directory to look up > which inode the "." entry refers to. Doesn't that seem a little > redundant, since the kernel already knows what the current directory is? > If the kernel is already caching the current directory table, it might > as well just cache the current directory's inode. > > Coming back to my original question, does the kernel really need that > "." entry? or is it purely for the user convenience? > > cheers, > > jz > Jason, I thought about your question when you first asked it, and again now. In a generic sense I can't think of a reason that the '.' entry is mandatory. As you say there seem to be ways to track the same info without have that specific directory entry. OTOH, I would assume the VFS (virtual file system) component of the Linux Kernel assumes that it is there. Greg -- Greg Freemyer -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
