[RndTbl] Unix command line challenge!

[Kevin McGregor]

Is there a way to untar a tar archive to stdout and use that output to recreate the archive by piping it back into tar? GNU tar has a transform option to change the file names. 

Sent from my iPhone

> On Oct 12, 2017, at 10:42, Adam Thompson <athompso at athompso.net> wrote:
> 
>> On 2017-10-12 08:59, Kevin McGregor wrote:
>> 
>> Given a gzipped cpio archive (12 GB!) with files in it like:
>>  
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/CILICEXP.xml
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/CILTSVTP.xml
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/C1LOOUPP.xml
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/CILTTRAL.xml
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/CILCSSPL.xml
>> wwdsvdccb101/root/data/ccb/ccbx/splapp/servers/myserver/tmp/.appmergegen_1347913274622/SPLWeb.ear/h7y1ba/data/xml/CILTCLGP.xml
>>  
>> How can I change the first component of the path to something else without unpacking the entire archive to disk first? Obviously I'll still have to un-gzip and de-cpio the whole 12GB while processing; I just don't want to put the whole thing on disk while I'm changing the path.
>>  
>> Any ideas?
>>  
>  
>  
> sed(1)  :-D
>  
> Seriously, I don't think it's possible.
> Almost all cpio(1)s support the "-r" flag for interactive renaming of files, but that doesn't sound like it would be fun for you.
> Best I can suggest is pre-create the directory structure you want, then pre-create a matching tree of symlinks.
>  
> e.g.:
>   # mkdir wwdsvdccb202
>   # ln -s wwdsvdccb202 wwdsvdccb101
>   # gunzip file | cpio <magical extract flags>
>  
> then cpio(1) will extract the files under wwdsvdccb202, thinking it's really under wwdsvdccb101.  If you can't do that in the current directory, then just fake it:
>   # mkdir /var/data/wwdsvdccb202
>   # ln -s /var/data/wwdsvdccb202 /tmp/wwdsvdccb101
>   # cd /tmp
>   # gunzip file | cpio <magical extract flags>
>  
> Sorry I can't be of more help :-(
>  
> -Adam
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