RFC: Snappy shell

Dustin Kirkland kirkland at canonical.com
Thu Jun 18 19:05:28 UTC 2015

On Thu, Jun 18, 2015 at 9:32 AM, Oliver Grawert <ogra at ubuntu.com> wrote:
> hi,
> Am Donnerstag, den 18.06.2015, 14:24 +0200 schrieb Zygmunt Krynicki:
>> Hey
>> So we can keep normal shell on port 22 and use ssh subsystems (like
>> sftp) to install a snappy-cli subsystem. Why? Then you can have a
>> Ubuntu command that ssh's into snappy cli. One port, many features. So
>> far I only know of sftp using this but the mechanism is generic.
> no, i meant it exactly the other way around ...
> by default on a standard snappy system a snappy shell runs on port
> 22 ...
> but if you deploy images in your cloud environment where your management
> software expects a proper ssh with login shell on port 22 you can use
> "ubuntu-device-flash --disable-snappy-shell" so that we still stay
> compatible with the established old way and do not lose the potential
> audience that uses tools that rely on ssh on port 22.
> such existing solutions will likely expect a bash or some other /bin/sh
> to be directly available on that port after you connect ... and might
> not be able to cope with explicitly calling "snappy bash" before issuing
> whatever shell command they use.

These, as well as Mark's suggestion about various snaps each providing
their own interactive shell-like interface, are cleanly addressed by
enabling end users (or particular gadgets) to set one of these shells
as the last line of ~/.profile, such that an interactive login drops
you straight into that program, while maintaining all of the benefits
of ssh and bash and friends ;-)

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