[lxc-devel] [PATCH 2/2] templates: use hardlink detection in rsync

[Michael H. Warfield]

On Mon, 2012-12-03 at 12:18 -0600, Serge Hallyn wrote:
> Quoting Dwight Engen (dwight.engen at oracle.com):
> > On Mon, 3 Dec 2012 10:47:26 -0600
> > Serge Hallyn <serge.hallyn at canonical.com> wrote:
> > 
> > > Quoting Dwight Engen (dwight.engen at oracle.com):
> > > > On Mon, 3 Dec 2012 10:04:13 -0600
> > > > Serge Hallyn <serge.hallyn at canonical.com> wrote:
> > > > 
> > > > > However one question is:  is -H ubiquitous?
> > > > 
> > > > I'm wondering why we don't just use the cp -a? It seems like cp is
> > > > far more likely to be installed than rsync? rootfs_path probably
> > > > doesn't already exist so it not like rsync is going to be faster?
> > > 
> > > The one advantage to me was that 'rsync -va /x/ /y' does the right
> > > thing whether or not /y already exists or not.  cp -a does not.  This
> > > just left the code tidier.
> > > 
> > > Is there a nicer clean one-line idiom to do that with cp?
> > 
> > I think cp -aT does what we want. You might want to add -u also.
> 
> Boy, that does not do what I expected based on the documentation, and
> having -t and -T invert args didn't help :)  But the little test below
> seems to do the right thing.

Interesting.  I also would have not expected for the same reasons.  I'm
noting that for future reference myself.

> I'll send a new patch using cp -T, thanks!

Yeah, thanks!

> #!/bin/bash
> rm -rf /tmp/d
> mkdir -p /tmp/d/a/e/f
> #mkdir -p /tmp/d/b
> cp -aT /tmp/d/a /tmp/d/b
> find /tmp/d
> 
> echo
> 
> rm -rf /tmp/d
> mkdir -p /tmp/d/a/e/f
> mkdir -p /tmp/d/b
> cp -aT /tmp/d/a /tmp/d/b
> find /tmp/d
> 
> echo
> 
> rm -rf /tmp/d
> mkdir -p /tmp/d/a
> touch /tmp/d/a/f
> #mkdir -p /tmp/d/b
> cp -aT /tmp/d/a /tmp/d/b
> find /tmp/d
> 
> echo
> 
> rm -rf /tmp/d
> mkdir -p /tmp/d/a
> touch /tmp/d/a/f
> ln -s /tmp/d/a/f /tmp/d/a/g
> ln /tmp/d/a/f /tmp/d/a/h
> mkdir -p /tmp/d/b
> cp -aT /tmp/d/a /tmp/d/b
> find /tmp/d
> ls -li /tmp/d/b
> 
> -serge

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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