[blfs-support] Complete Backup of {,B}LFS

Dan McGhee beesnees at grm.net
Mon Dec 23 05:59:22 PST 2013


On 12/23/2013 06:01 AM, akhiezer wrote:
>> Date: Mon, 23 Dec 2013 00:43:13 +0100
>> From: Aleksandar Kuktin <akuktin at gmail.com>
>> To: blfs-support at linuxfromscratch.org
>> Subject: Re: [blfs-support] Complete Backup of {,B}LFS
>>
>>> This looks really interesting and I want to "play" with it. But what
>>> I want *is* a clone, an exact copy, of what I have now.
>>>
>>> Dan
>>>
>>>
>> On the subject of cloning filesystems (as opposed to cloning devices),
>> I come up blank with names of programs that can do that, even though
>> there is probably at least one program that can do that.
>>
>
> 'e2image' (part of e2fsprogs pkg) might be partly of some use there, in the
> wider-picture: but I'd say for the present task you really want dd or the
> find/cpio combination; either of them will do the job just fine. If you
> need 100% identical data - incl metadata, timestamps, &c - then I'd say use
> dd. Whereas, working at the filesystem-level - as you normally would with
> find/cpio, cp, tar, cat, &c - you run the 'risk' of at least some metadata
> (e.g. timestamps on dirs) being changed in source &/or target. IME, for
> working at the filesystem-level, the find/cpio combination will get you
> 100% identical data-copy (I've never encountered find/cpio 'choking' on any
> filesys-objects), and near-100%-identical metadata-copy (e.g. via those '-a'
> & '-m' cpio flags).
I am always quite interested in what one word or phrase means to 
different people. In this case, my use of "clone" was not as precise as 
it could have been. I also enjoy learning about the capabilities and 
uses of the various linux tools. Then, even if I only "darkly" remember, 
I can look up the tool and learn how to use it.

When I said "clone" I didn't think about the partition size, where the 
info was located or the metadata. However, my main concern was 
preservation of ownership, group and permissions. But with the remarks 
in this thread, I want the times preserved now--I've used them before in 
"find" for the tests --newer and !--newer.

I completed the backup, but now want to do it again to insure all of 
this. I used <cp -a> the last time because of permissions. The reason I 
didn't use the find|cpio combination was that ownersip wasn't preserved. 
I read the cpio info and saw this--

> |--no-preserve-owner|
>     Do not change the ownership of the files; leave them owned by the
>     user extracting them.
>

To me that phrase "leave them owned...." says that the files will be 
owned by me when I'm done and seems to contradict the first part of the 
sentence which is what I wanted to have happen.

If I use "--no-preserve-owner" will the ownership, group and permissions 
remain as they are, or do they get changed?

Dan
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