Moving/merging a filesystem back into /

Charles Marcus CMarcus at
Tue Dec 3 06:11:28 MST 2013

On 2013-12-02 5:55 PM, Kevin Korb <kmk at> wrote:
> mount/dev/sda3 /mnt/gentoo/
> You might have to specify more options here.  Check what they are
> before you shut down.

Ok, thinking about this more... since booting off a liveCD means I'm not 
using the systems fstab, so I have to specify the filesystem too?

/ is ext3, so just use the same options as in fstab:

mount -o noatime /dev/sda3 /mnt/gentoo/ ?

Or do I need to specify the filesystem type?

mount -t ext3 -o noatime /dev/sda3 /mnt/gentoo/ ?

Hmmm... and any concerns about the filesystem for /usr changing from 
reiserfs to ext3?

> - --numeric-ids won't matter if rsync isn't networking but it is an 
> important one to know about.

Someone on the gentoo list claimed that because when booting from a 
liveDVD you're essentially accessing the filesystem from 'another 
system', that it was (possibly very) important to use --numeric-ids, 
someone else then backed him up, and no one has said anything to the 
contrary, so... are you sure?

Doesn't matter though, since it can't hurt anything, I'll always use it 
regardless... ;)

> ext[34] can remember acl as a default mount option. I have no idea if 
> reiserfs can do that or not and I recommend against using reiserfs at all.

I know, but this system was built over 8 years ago (when gentoo still 
recommended reiserfs), and runs like a champ, so no desire to 'fix what 
ain't broke'... anyway, acls are not enabled on it, so no worries...


> For Gentoo if you don't have USE=caps or USE=caps-ng set then you
> probably don't have and xattrs in /usr

emerge --info shows neither:

USE="3dnow acl amd64 bash-completion berkdb bzip2 cli cracklib crypt 
curl cxx dovecot-sasl dri fam fortran gd gdbm iconv mmx modules mudflap 
multilib ncurses nls nptl openmp pam pcre readline sasl session snmp sse 
sse2 ssl tcpd truetype unicode vhosts xml zlib"

So, no -X...

> That command will not list symlinks.  Anything it lists is a hard link.

Weird, you're right... dunno how I confused myself there...

> - -H is only hard links. Symbolic links are handled in -a.

Ok, good, thanks, definitely want -H......

> If you want to watch the --progress output then -P is a perfectly fine
> shortcut for it.  -p is --perms which is unrelated and part of -a.

Gotcha, thanks...

>> So, to be safe, use --numeric-ids...? 
> It won't hurt.  It is just extra typing but it could be considered to
> be a good habit for when it does matter.

Understood... and since it can't hurt anything, but can prevent serious 
problems... :)

> One more thing I didn't mention before...
> Since /usr is pretty static you could "prime the copy" by doing the
> rsync initially to / while the system is running.  Then you
> would really only have an mv and and fstab edit to do from your live
> environment.  You could probably even do those right before rebooting
> if you are careful.
> Even on something more dynamic like /home you can still do an initial
> copy then update it from the live environment.

Ok, so... if I wanted to do this, would I need to add anything to the 
rsync command on the subsequent run(s)?

So, looks like the command I'll be using:

rsync -avHP --numeric-ids /mnt/gentoo/oldusr/ /mnt/gentoo/usr/

Thanks very much Kevin for your time and help...


Best regards,

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