rsync - Feb 2024 - rsync replacing symlinks without warning (resend)

rsync's -v is fairly useless.  Learn to use -i instead or in addition to.

On 2/4/24 12:58, Andreas Gruenbacher via rsync wrote:
> Hello,
> 
> when trying to rsync files between hosts, I ran into a surprising case
> in which rsync replaces a symlink with a directory, with no indication
> of any kind.
> 
> In the following reproducer, rsync is called as follows:
> 
>    rsync --verbose --recursive --relative --delete a/./lib/modules b/
> 
> Directory b contains a 'lib' symlink pointing to 'usr/lib',
and rsync
> removes that and replaces it with a directory.
> 
> In my real-world use case, this caused '/lib' ->
'/usr/lib' symlinks
> to be replaced with '/lib' directories, which left the receiving
test
> machines in a fairly sad state.
> 
> I have since figured out that I can get rsync to behave as expected by
> adding the --keep-dirlinks option, but ...
> 
> it's very unfortunate that when rsync does that kind of thing, it
> leaves no indication in the 'rsync --dry-run' and 'rsync
-v' output.
> Could that please be fixed?
> 
> Thanks,
> Andreas
> 
> 
> #! /bin/sh
> 
> tmp=$(mktemp -dt ${0##*/}.XXXXXXXXXX)
> trap 'cd /; rm -rf $tmp' EXIT
> cd "$tmp"
> 
> umask 022
> 
> mkdir -p a/lib/modules
> echo foo > a/lib/modules/foo
> 
> mkdir -p b/usr/lib/modules
> ln -s usr/lib b/lib
> 
> show() {
>      find "$@" | xargs stat -c "%F %N" | sort -k2
> }
> 
> echo "from:"
> show a
> 
> echo
> echo "to:"
> show b
> 
> echo
> echo "rsync:"
> rsync \
>      --verbose \
>      --recursive \
>      --relative \
>      --delete \
>      a/./lib/modules \
>      b/
> 
> echo
> echo "to:"
> show b
> 
> # SCRIPT OUTPUT with rsync 3.2.7:
> # =============================> > # from:
> # directory 'a'
> # directory 'a/lib'
> # directory 'a/lib/modules'
> # regular file 'a/lib/modules/foo'
> #
> # to:
> # directory 'b'
> # directory 'b/usr'
> # directory 'b/usr/lib'
> # directory 'b/usr/lib/modules'
> # symbolic link 'b/lib' -> 'usr/lib'
> #
> # rsync:
> # sending incremental file list
> # lib/
> # lib/modules/
> # lib/modules/foo
> #
> # sent 160 bytes  received 47 bytes  414.00 bytes/sec
> # total size is 4  speedup is 0.02
> #
> # to:
> # directory 'b'
> # directory 'b/lib'
> # directory 'b/lib/modules'
> # directory 'b/usr'
> # directory 'b/usr/lib'
> # directory 'b/usr/lib/modules'
> # regular file 'b/lib/modules/foo'
> 
>

On Sun, Feb 4, 2024 at 7:20?PM Kevin Korb via rsync
<rsync at lists.samba.org> wrote:
> rsync's -v is fairly useless.  Learn to use -i instead or in addition
to.
Well, note that I didn't say anything about the lib/ directory in that
command; it's just that rsync decided to remove the symlink component
from the path lib/modules/.

Wouldn't it be more useful to make it obvious in the --verbose and
--dry-run output what rsync has actually decided to do instead of
blaming the user, which is what you're doing? Especially if the
behavior is all but self-explanatory?

Thanks,
Andreas
> On 2/4/24 12:58, Andreas Gruenbacher via rsync wrote:
> > Hello,
> >
> > when trying to rsync files between hosts, I ran into a surprising case
> > in which rsync replaces a symlink with a directory, with no indication
> > of any kind.
> >
> > In the following reproducer, rsync is called as follows:
> >
> >    rsync --verbose --recursive --relative --delete a/./lib/modules b/
> >
> > Directory b contains a 'lib' symlink pointing to
'usr/lib', and rsync
> > removes that and replaces it with a directory.
> >
> > In my real-world use case, this caused '/lib' ->
'/usr/lib' symlinks
> > to be replaced with '/lib' directories, which left the
receiving test
> > machines in a fairly sad state.
> >
> > I have since figured out that I can get rsync to behave as expected by
> > adding the --keep-dirlinks option, but ...
> >
> > it's very unfortunate that when rsync does that kind of thing, it
> > leaves no indication in the 'rsync --dry-run' and 'rsync
-v' output.
> > Could that please be fixed?
> >
> > Thanks,
> > Andreas
> >
> >
> > #! /bin/sh
> >
> > tmp=$(mktemp -dt ${0##*/}.XXXXXXXXXX)
> > trap 'cd /; rm -rf $tmp' EXIT
> > cd "$tmp"
> >
> > umask 022
> >
> > mkdir -p a/lib/modules
> > echo foo > a/lib/modules/foo
> >
> > mkdir -p b/usr/lib/modules
> > ln -s usr/lib b/lib
> >
> > show() {
> >      find "$@" | xargs stat -c "%F %N" | sort -k2
> > }
> >
> > echo "from:"
> > show a
> >
> > echo
> > echo "to:"
> > show b
> >
> > echo
> > echo "rsync:"
> > rsync \
> >      --verbose \
> >      --recursive \
> >      --relative \
> >      --delete \
> >      a/./lib/modules \
> >      b/
> >
> > echo
> > echo "to:"
> > show b
> >
> > # SCRIPT OUTPUT with rsync 3.2.7:
> > # =============================> > > > # from:
> > # directory 'a'
> > # directory 'a/lib'
> > # directory 'a/lib/modules'
> > # regular file 'a/lib/modules/foo'
> > #
> > # to:
> > # directory 'b'
> > # directory 'b/usr'
> > # directory 'b/usr/lib'
> > # directory 'b/usr/lib/modules'
> > # symbolic link 'b/lib' -> 'usr/lib'
> > #
> > # rsync:
> > # sending incremental file list
> > # lib/
> > # lib/modules/
> > # lib/modules/foo
> > #
> > # sent 160 bytes  received 47 bytes  414.00 bytes/sec
> > # total size is 4  speedup is 0.02
> > #
> > # to:
> > # directory 'b'
> > # directory 'b/lib'
> > # directory 'b/lib/modules'
> > # directory 'b/usr'
> > # directory 'b/usr/lib'
> > # directory 'b/usr/lib/modules'
> > # regular file 'b/lib/modules/foo'
> >
> >
>
> --
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