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.

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On Oct 12, 2017, at 10:42, Adam Thompson athompso@athompso.net wrote:

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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