On Tue, 12 Nov 2002, Eli Billauer wrote: > Hello Guy & all. > > Personally, I didn't understand much of you explanation.
i'll try to write it again, with a more illustrative example. > I didn't understand why a rescue floppy won't work. The only thing I realized, > was that rather than correcting the links, you create a /bigdisk/etc that > points to /etc. Looks like a nice solution, which I may have adopted myself, > if I wasn't so eager to get on. here is the scenario: lets talk about an upgrade from RH version X, to version X+1 (the case i stumbled upon, that finally made me understand why full-path symbolic links can be bad): suppose that i have a '/' partition and a '/bigdisk' partition. suppose that my '/usr' is a symlink to '/bigdisk/usr'. i insert the new RH version CD and choose to 'upgrade'. the upgrade program now looks at the 'etc/fstab' on my '/' partition, and sees which filesystems i use, and so it mounts them: my '/' is mounted under '/root'. my '/bigdisk' is mounted under '/root/bigdisk'. now the upgrade wants to upgrade a package that exists under my '/usr'. it assumes the package can be found (during the upgrade process) under '/root/usr'. this is, however, a symlink to '/bigdisk/usr'. however, currently 'bigdisk' is mounted under '/root/bigdisk', and there is no '/bigdisk/usr' - only a '/root/bigdisk/usr' directory, and thus the upgrade will fail. if my /usr symlink was made relative (i.e. under my '/', usr was a symlink to 'bigdisk/usr') the link would still have worked during the upgrade process: under /root, i'll have a 'usr' link, pointing to 'bigdisk/usr', which translates (again, during the upgrade) to '/root/bigdisk/usr' - which is correct. the same issue, btw, would exist if i wanted to mount my partitions under a different operating system (e.g. via an NFS mount). hope this makes the need for relative links clear. > My 'absolute links' are all corrections of the cases, where the root directory > was referred to as ../../...(and so on). If I want /etc/passwd, why go > ../../../etc/passwd? If I mean root, go root. In that sense, the link > correction looks better than the previous trick. but you don't realy mean root - you mean a specific root. and if that root changes its location - you'll want to link to change the location it points to as well - and that will happen only with proper relative links - not with absolute links. and that, my friend, is something i wish would have been explained to me years ago - rather then understood during a bad system upgrade, late at night ;) > I agree that things become messy when new packages are installed, which is > exactly the reason why I install all the packages from the beginning. And when > you want a new package, it's a headache anyhow... but what about updating existing pacakges, e.g. because a security bug was found (i know, you don't care about those ;) ) or because of some other reason (e.g. a fix to a bug that you stumbled over - you would care about those). not to mention the case of upgrade to a newer version of the distribution - you will probably do that in a few years ;) -- guy "For world domination - press 1, or dial 0, and please hold, for the creator." -- nob o. dy -------------------------------------------------------------------------- Haifa Linux Club Mailing List (http://www.haifux.org) To unsub send an empty message to [EMAIL PROTECTED]
