Messages in this thread | | | Date | Sun, 16 Jan 2000 11:31:33 -0800 (PST) | From | Robert Dinse <> | Subject | Re: a garbage-collected file system |
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On Sat, 15 Jan 2000 Horst von Brand <vonbrand@sleipnir.valparaiso.cl> wrote: > > david.madore@ens.fr (David Madore) said: > > Bruce Janson has pointed out to me the following interesting fact: > > whereas some people have been criticizing as "un-unixy" my proposal to > > admit hard links between directories, it was actually permitted in the > > very first versions of Unix, as shown in the following transcript of a > > test I just made: > > On some ancient VAX version of Ultrix this was also possible in some cases. > It was useful mostly for creating headaches later on, like undeletable > directories, but unlink worked on directories too... Nice to have if you > managed to loose .. somewhere, though. Mandatory fsck(8) afterwards. If > this "feature" was removed later, it was probably just an oversight (aka > bug). AFAIK, no Unix had other than the current reference counting garbage > collection anyway, without which this won't ever work.
For what it's worth, SunOS 4.1.4 would also let you do this. The 'ln' command wouldn't, but if you were super-user, /usr/etc/link would allow you to make hard-links to directories, and /usr/etc/unlink would allow you to unlink them.
I played with them somewhat, and never found anything that it broke by hard linking directories, fsck seemed to handle it fine. Unlinking a directory where there were still files and it was the last link would of coarse orphan those files.
I never found any use for this capability that couldn't equally well have been served with a sym-link, but it was there.
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