rsync - Apr 2004 - Another feature proposal and implementation plan: --strip-prefix

Here's another feature I'd like to have:

Suppose you're copying a source file /a/b/c/d/e/f/g/h/myfile and you 
want it stored on some other filesystem /backup, but you want the source 
path to be truncated so that the file actually ends up as: /backup/h/myfile.

This comes up (in particular) when doing backups of windows machines via 
cygwin; you end up with a phony base directory /cygdrive/. When users go 
to see their backups, they become confused! This option would eliminate 
this problem.

I'd like to add this behavior, similar to the patch -p option.

I'm uncertain whether the syntax should be 
--strip-prefix=/a/b/c/d/e/f/g, or --strip-prefix=7. The former would 
allow us to detect situations in which we were being asked to copy files 
that did not have the expected prefix and to complain loudly (or 
silently ignore the strip prefix directive for that file?) The latter 
would be more like patch -p, but I think it's less safe. Perhaps 
multiple --strip-prefix directives should be allowed so that a single 
invocation of rsync can handle more complicated situations.

I think this can be relatively cleanly implemented in recv_files; in 
fact, the line "fnamecmp=fname;" in reciever.c seems to be exactly the
hook required. Like my previous email, I would like to ask for advice 
and suggestions so that my implementation will be most useful!

Thanks,

-Ed

Wouldn't it be easier just to create a softlink on the cygwin machine so 
that you could access C: from /c ?

Or for that matter, if these are easily-confused Windows users, just 
begin the Samba (or other SMB) share south of the cygwin/ on the rsync 
machine?
> Here's another feature I'd like to have:
> 
> Suppose you're copying a source file /a/b/c/d/e/f/g/h/myfile and you 
> want it stored on some other filesystem /backup, but you want the source 
> path to be truncated so that the file actually ends up as: 
> /backup/h/myfile.
> 
> This comes up (in particular) when doing backups of windows machines via 
> cygwin; you end up with a phony base directory /cygdrive/. When users go 
> to see their backups, they become confused! This option would eliminate 
> this problem.
> 
> I'd like to add this behavior, similar to the patch -p option.
> 
> I'm uncertain whether the syntax should be 
> --strip-prefix=/a/b/c/d/e/f/g, or --strip-prefix=7. The former would 
> allow us to detect situations in which we were being asked to copy files 
> that did not have the expected prefix and to complain loudly (or 
> silently ignore the strip prefix directive for that file?) The latter 
> would be more like patch -p, but I think it's less safe. Perhaps 
> multiple --strip-prefix directives should be allowed so that a single 
> invocation of rsync can handle more complicated situations.
> 
> I think this can be relatively cleanly implemented in recv_files; in 
> fact, the line "fnamecmp=fname;" in reciever.c seems to be
exactly the
> hook required. Like my previous email, I would like to ask for advice 
> and suggestions so that my implementation will be most useful!
> 
> Thanks,
> 
> -Ed
>

On Wed, Apr 14, 2004 at 07:36:23PM -0400, Edwin Olson
wrote:
> Suppose you're copying a source file /a/b/c/d/e/f/g/h/myfile and you 
> want it stored on some other filesystem /backup, but you want the source 
> path to be truncated so that the file actually ends up as:
/backup/h/myfile.
(I'm assuming that you're using the --relative option, or you
wouldn't
be having this issue.)

If you're pushing dirs, do a chdir before calling rsync and then copy a
relative path:

cd /a/b/c/d/e/f/g
rsync -avR h/myfile remote:/backup

If you're pushing OR pulling, you can accomplish the same thing using
--files-from:

echo h/myfile | rsync -av --files-from=- remote:/a/b/c/d/e/f/g /backup

With --files-from, the source path specifies the default dir, and the
--relative option is on by default, so you'd end up with your desired
result.

..wayne..