cpio and tar are loosing flags (and a panic message without trace)

Matthew Dillon dillon at apollo.backplane.com
Sat Aug 27 04:58:19 GMT 2005

:Thank you, I know cpdup but I haven't known that it's flags aware!
:Unfortunately I need to write to a raw device, I guess there's no way for=20
:cpdup without a filesystem...
:I guess cpio and tar really should take care about flags. Am I wrong?

    cpio won't do it, tar won't do it, dump only does whole partitions,
    cpdup is not an archiver.  Hmm.

    I can think of two possibilities.  First, use a MFS or VN block device,
    create a filesystem, and use cpdup, then gzip the file representing
    the backing store.  Since the extra space in the filesystem will contain
    zeros (you should make sure it does, that is), it should compress pretty
    well.  Second, use cpio and then do a separate 'find' or 'ls' or 
    something to get the chflags info and write a script that restores
    the flags after unpacking.

    They are both pretty narley solutions.

    Hmm.. wait a sec... I just thought up of another possibility... take
    the tar or cpio source code and modify it to also save and restore
    the chflags data.  It won't be a 'standard' utility any more, but it
    WILL work for your needs.  Call it by another name so there's no
    confusion.  That might be your best bet, actually.


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