rsync - Apr 2003 - need to modify file data before storing it on destination

I'd like to be able to store remote files compressed or encrypted
or both.  I think this could be supported in a general way by
having:

    1. an rsync option --remotefilter=command that specifies a
       remote command that rsync pushes file data through before
       storing it on disk.  This option would imply --whole-file.
    2. an rsync option --times-only so that rsync would consider
       only the modification time of the remote file when deciding
       whether to update it.  This is needed so that rsync would
       ignore the file size differences of compressed remote files.

I'm willing to contribute code to implement this.  I'd like to see
this functionality integrated in the standard rsync distribution in
some form.  I distribute a disk-to-disk backup tool that relies on
rsync (see http://freshmeat.net/projects/snapshot/ ) and I'd prefer
not to distribute patches to rsync to provide this functionality.

On Mon, Mar 31, 2003 at 12:37:27PM -0800, Kyle Jones
wrote:
> I'd like to be able to store remote files compressed or encrypted
> or both.  I think this could be supported in a general way by
> having:
> 
>     1. an rsync option --remotefilter=command that specifies a
>        remote command that rsync pushes file data through before
>        storing it on disk.  This option would imply --whole-file.
>     2. an rsync option --times-only so that rsync would consider
>        only the modification time of the remote file when deciding
>        whether to update it.  This is needed so that rsync would
>        ignore the file size differences of compressed remote files.
Well, with that you have just disabled the primary
characteristic of rsync.  I'm not saying that a utility that
identifies files that have changed for a compressed remote
storage, just that this isn't rsync.

There have been several proposals that are at least somewhat
consistent with rsync for doing this.  Look in the list
archives.  Another approach is to create your own utility.
The GPL lets you even steal or build on rsync or other code
for the purpose.

Of course there are also compressed filesystems and
compressed loopback devices or using an existing tool (i
assume there is at least one) that already do this.

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw@pegasys.ws

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