Remote usage script updated

[Michal Sojka]

On Wed, 09 Feb 2011, Jesse Rosenthal wrote:
> Michal,
> 
> On Sun, 06 Feb 2011 00:58:29 +0100, Michal Sojka <sojkam1 at fel.cvut.cz> wrote:
> > Hmm, this code worked well with dropbear ssh server but it seems that
> > with openssh server the result is not that good. Namely, if the master
> > connection is dead, the command running true blocked for a long time.
> 
> Seemed to work okay for me when I played around with it a bit (in
> different circumstances, and with a confused laptop waking up from
> hibernation). But I'll hold off on updating it till I can figure out the
> most reliable way.

Hi Jesse,

I've just found that there is a SSH option called ControlPersist and
this is the missing piece to reliable connection sharing for notmuch
remote script. This option is available since openssh 5.6
(http://www.openssh.org/txt/release-5.6) with a fix of race conditions
in 5.7 (http://www.openssh.org/txt/release-5.7).

Now I have in my script the following command:
  ssh -x -a -oControlMaster=auto -oControlPersist=600 -S $SOCKET $USER@$SSH_HOST $NOTMUCH_REMOTE_BIN ${CMD} ${args}

where SOCKET="${CACHE}/.ssh-socket-${USER}@${SSH_HOST}" and it works
perfectly.

Unfortunately, this option is not supported in recently released Debian
Squeeze but from http://bugs.debian.org/594295 seems that it might be
supported later, perhaps in a point release.

-Michal