rsync 3.1.0/3.1.1 incompatible with 2.5.7

[Ole Tange]

On Sat, Jul 26, 2014 at 1:49 AM, Wayne Davison <wayned at samba.org> wrote:
> On Fri, Jul 25, 2014 at 11:50 AM, Ole Tange <tange at gnu.org> wrote:
:

Thanks for the explanation.

>> My question is now: What should I do as a developer?
>
> There aren't any particularly easy answers for dealing with an old bit of
> software that is refusing to play nice with newer software.  One possibility
> is for your wrapping code to do a configure pass that checks the rsync
> version on both of the hosts and figures out if one is too old (2.6.0 and
> newer are fine, so only 2.5.7 and older have this issue) and one is too new
> (3.1.0 is the first to start using protocol 31). If that occurs, you can
> specify the --protocol=30 option on the newer rsync to avoid the issue.

Finding the remote version will be slow. Is there any reason why I
don't just look at the local version, and if $version >= 3.1.0 then
add '--protocol=30'. When will that break down?


/Ole