Hello, On Thu, Jul 30, 2009 at 11:12:03AM +0200, Arne Babenhauserheide wrote: > Am Donnerstag, 30. Juli 2009 10:48:00 schrieb Carl Fredrik Hammar: > > A cleaner solution would be to first mount a hypothetical ``filterfs'' > > that removes the files, and then do a unionmount on top of that. Also you > > could just simply set a lib.so.1 -> lib.so.3 symlink in the mountee, which > > would shadow the underlying lib.so.1. > > That's definitely sounds cleaner. > > Could a filterfs and unionmount be combined to a fully transparent writeable > filesystem which uses a readonly filesystem as base? > > That way I could use a LiveCD as base and store my changes on a USB-stick. To > setup my environment (including my user data) I'd just set my "this is my > system" translator on root. > > $ settrans -a / mine /mnt/usb/arne.tbz
You mean union-mounting ``mine'' here, right? Note that you still require root privileges to set a translator on / . (At least I'm not allowed to do that in my instance of the Hurd). When I tried to set a translator on / as root, I didn't really succeed either, but this could be because I was doing something wrong. I did the following: # settrans -a / <trans> I can see no difference between the output of ls / before mounting <trans> and after it, although I can see the translator process running. Also, I can settrans -gf / , and it kills <trans>, and I still can ls / quite successfully. However, whenever I do fsysopts /, I never see anything but the expected ext2fs.static translator. > Other users would still see the original system, but I'd work in my > own environment. I'm not sure it is really possible, since you are setting a translator on / . > It could even use a version tracking backend, which tells it which files need > to be filtered and added. That way a change in the base system could be > reflected in the filterfs. This would then use a lot more space, but if the > main repository would be used as a base by all users, that space would only > be > required once. I'm sorry, but I cannot see why you need a version tracking back-end in this case. Actually, what I cannot fully understand is the ``version tracking'' part :-) If your point is that filterfs should show only *a part* of the base filesystem, then you don't really need any version tracking. Just tell the all-mighty filterfs to mask away the corresponding files. Do I understand something wrong? > Instead of that it could also just access an installed package database for > filtering installed programs - in Gentoo that would just mean accessing the > files inside /var/db and telling the filterfs (or a preprocessor) not only to > mask files but to mask installed packages so they can get replaced completely > by the users installed packages. So, your personal setup also includes the modified files from some system directories, right? (like /var/db, /etc/) > I could have a Gentoo where every user can modify the whole system without > affecting any other user. This sounds cool :-) And also very much like sub-hurds, actually ;-) I don't know whether sub-hurds must always use a chrooted environment, but, even if not, working within one and doing a chroot explicitly gives you a personal world per user, too. Regards, scolobb
