Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!bloom-beacon!gatech!ulysses!hector!ekrell From: ekrell@hector..UUCP (Eduardo Krell) Newsgroups: comp.unix.wizards Subject: Re: symbolic links are a botch Message-ID: <2727@ulysses.homer.nj.att.com> Date: Mon, 13-Jul-87 16:15:53 EDT Article-I.D.: ulysses.2727 Posted: Mon Jul 13 16:15:53 1987 Date-Received: Wed, 15-Jul-87 00:37:17 EDT References: <2629@ulysses.homer.nj.att.com> <390@murphy.UUCP> <898@rtech.UUCP> <8738@tekecs.TEK.COM> <241@nuchat.UUCP> Sender: daemon@ulysses.homer.nj.att.com Reply-To: ekrell@ulysses (Eduardo Krell) Organization: AT&T Bell Labs, Murray Hill Lines: 22 In article <241@nuchat.UUCP> steve@nuchat.UUCP writes: > >Instead of allowing directories to be links to another directory, >have an object with the superficial semantics of a directory but >implementing a "copy-on-write" window onto a search path of other >directories, perhaps chained to arbitrary depth. I have already done exactly what you describe. We have an experimental unix kernel with this facility added. It's very similar to the viewpathing concept found in build and nmake (aka 4th generation make). Basically, one can create a "continuation" directory, which will be searched whenever a filename is being looked up and it's not found in the current directory. That continuation directory can have more continuation directories chained in a kind of linked list, and they are all searched in turn. If the same file exists in 2 or more of these directories, only the first one will ever be seen. File are always created in the first (original) directory. Only file lookups follow these continuation pointers. Eduardo Krell AT&T Bell Laboratories, Murray Hill {ihnp4,seismo,ucbvax}!ulysses!ekrell