configure --with-rsh=CMD and default blocking-IO support

[Dave Dykstra]

On Tue, Feb 05, 2002 at 09:38:04PM -0800, Wayne Davison wrote:
> On Wed, 6 Feb 2002, Martin Pool wrote:
> > OK, I agree --with-rsh should go in, but I think putting magic
> > characters into it is needlessly confusing.  I would feel much better
> > about a separate configure option to set the default O_NONBLOCK mode.
> 
> The complicating factor then becomes: how does the RSYNC_RSH environment
> variable interact with this default O_NONBLOCK mode, and how can the
> default blocking be changed via the environment?  I came up with the
> magic character idea in order to try to keep things simple (using only
> one environment variable instead of trying to keep two different ones in
> sync).  I admit that it's quirky, though.
> 
> So the obvious alternative is something like this:
> 
>     export RSYNC_RSH=ssh
>     export RSYNC_BLOCKING_IO=1
> 
> Perhaps a better idiom might be allow RSYNC_RSH to begin with a
> command-line option?  If the string begins with "--blocking-io " we
> strip it off and twiddle that command-line flag?  If we want to make
> this orthogonal we could also add support for the --non-blocking-io
> command-line option and allow this string to appear at the start of
> the RSYNC_RSH value.  What do you think of something like this?
> 
>     export RSYNC_RSH='--blocking-io /usr/bin/ssh -l username'
>     export RSYNC_RSH='--non-blocking-io rsh'

Of the proposed alternatives, I like this latter the best, changing 
--non-blocking-io to --no-blocking-io.

I added --no-blocking-io and --no-whole-file command line options
yesterday.

- Dave Dykstra