Re: remove files from archive

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On 01/06/2019 17:55, Matus UHLAR - fantomas wrote:
> Hello,

Hello,

> 
> I have a DAR archive into which some files got that don't belong to
> it. Is is possible to just remove files from the archive?

nop, this is not possible, sorry

> 
> from what I've seen, I could merge one archive into another,
> excluding files, but that's not ideal...

yes, this is the only way to go forward with your need using dar

> 
> I use dar 2.5.8 (from debian package)

For the details:

First, there is no way at system level to remove data from the middle
of a file. What you can do is to copy all data laying after the part
to be removed in order to have it sticked with the part that stay
before the removed part. Then you can truncate the file for it be shorte
r.

So in any case whatever the tool you use, you end up by copying data
and often much more that the amount to be remove.

Dar cannot even do that because file's data is referred in the
catalogue by the position it has in the archive: if you move data, you
have to change index values (data, data CRC, Extended Attributes,
Extended Attributes CRC, FSA, FSA CRC, delta signature, delta
signature CRC, and so on for each give file. And What if you have
slicing? This is even more time consuming as you have to copy data
between slices...  And what if the archive is ciphered? And what if
some on-fly hash file have been computed (--hash option)?

You guessed? The simplest way to do all that is to rebuild an archive
with only the data to be kept, this is exactly what the merging
operation does :)


> 
> thanks


Cheers,
Denis
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