[Nottingham] Gentoo experts: emerge file collisions!?

Martin martin at ml1.co.uk
Fri Aug 14 19:22:51 UTC 2009

Richard Ward wrote:
> Martin wrote:
>> So... What is the procedure to complete the update without breaking the 
>> system the update is running on?
>> (Or is this just a case of over-caution in portage?)
>> Cheers,
>> Martin
> Ok, I think the following should work, but *please* either backup your 
> root partition or make a copy and try it in a chroot on the copy first, 
> obviously a system with a broken glibc is going to be a huge PITA.

I thought that might be the case... Backups done.

> It may make it easier to first build a binary package for glibc, that 
> way you won't have to recompile every time you try something, and you'll 
> have a convenient backup of all the files that glibc wants:
> emerge glibc --buildpkgonly

That ran smoothly finishing with:

 >>> Completed installing glibc-2.9_p20081201-r2 into 

ecompressdir: bzip2 -9 /usr/share/man
ecompressdir: bzip2 -9 /usr/share/info
making executable: usr/lib/libc.so
making executable: usr/lib/libpthread.so
 >>> Done.

> Then do `ls $PKGDIR' to check the file is there. next time you want to 
> try and install this glibc version you can use:

Well... $PKGDIR isn't set and there's nothing in "/var/tmp/portage". 
Nothing in "/var/tmp/binpkgs" either :-(

Or should I be looking in some other default location?

OK... So I've now set in /etc/make.conf:


and I'm rerunning the "emerge glibc --buildpkgonly". See if I get the 
binaries this time.

Next steps later tonight!

> emerge -K glibc
> The best thing to do is probably to just temporarily disable collision 
> detection:
> COLLISION_IGNORE="/" emerge glibc
> With any luck thats all it will take, check stuff is working, re-emerge 
> stuff to use the new glibc, and move on.
> If, however, vital files turn up missing/broken, you can just `emerge -k 
> glibc' again afterwards, or if that doesn't work due to missing files 
> just mount your system in a live distro or similar, untar the package 
> that emerge built, and dump the files in their correct locations.
> Once thats done it may be an idea to re-emerge your whole system, 
> starting with gcc.
> I you get problems of vital utilities breaking the process half way 
> through because they won't work with the new libc or without the missing 
> files, you can start the process again but first re-emerge them with 
> USE="STATIC" so that they will no longer need the shared libraries (eg 
> tar, wget).
> Keep us posted on how it goes, and do make a backup first!
> Richard

Phew! Thanks for that lot.

> P.S.
> I've never used one, but there are such things as overlay filesystems, 
> where you mount a file system read-only, then mount another one 'on top' 
> of it, so it appears from your point ov view you are modifying the 
> original system, but when you get rid of the overlay the original is 
> unmodified. It strikes me this would be perfect for doing what you are 
> trying to do, and would save all the time it takes to to a backup.

LVM or filesystem snapshots (or overlays) are indeed rather nice and 
definitely the way to go!

Still not sure if unionfs is good or just good for confusion...

> P.P.S
> Make a backup first! :)

Very wise :-)


Martin Lomas
martin at ml1.co.uk

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