SSH: Running single commands from SSH command line

Hi,

I have got a suggestion for future ZyNOS releases:

It would be nice to be able to run single commands via SSH on the switches instead of opening a login shell. This would help to orchestrate a bigger amount of switches by (client-side) scripting and might allow easier/better monitoring.

Example:

To run a command like "show system-information", instead of...

$ ssh admin@192.168.1.1
admin@192.168.1.1's password:
Copyright (c) 1994 - 2017 Zyxel Communications Corp.
XGS2210# show system-information

Product Model        : XGS2210-28
System Name        : XGS2210
System Mode        : Standalone
System Contact        :
System Location        :
System up Time        :    25:56:29 (8e806a ticks)
Ethernet Address    : 5c:e2:8c:5e:24:fc
Bootbase Version    : V1.0 | 01/25/2016
ZyNOS F/W Version    : V4.50(AAZJ.0) | 09/08/2017
Config Boot Image     : 1
Current Boot Image     : 1
Current Configuration     : 1
RomRasSize        : 7338278
XGS2210# exit
Write failed: Broken pipe
$

... one could execute a single command on the switch like this instead:

$ ssh admin@192.168.1.1 -- show system-information
admin@192.168.1.1's password:
Product Model        : XGS2210-28
System Name        : XGS2210
System Mode        : Standalone
System Contact        :
System Location        :
System up Time        :    25:56:29 (8e806a ticks)
Ethernet Address    : xx:xx:xx:xx:xx:xx
Bootbase Version    : V1.0 | 01/25/2016
ZyNOS F/W Version    : V4.50(AAZJ.0) | 09/08/2017
Config Boot Image     : 1
Current Boot Image     : 1
Current Configuration     : 1
RomRasSize        : 7338278
$

So a script could gather and process the output.

For even better processing it would be nice if an exit code would be set, so the script/caller can determine whether an error (and with different exit codes: which error) has occured without the need to parse the output.
Also sending error/warning messages to stderr instead of stdout would be great.

Alternative syntax (if easier to implement) could be quoting the complete command:
$ ssh admin@192.168.1.1 -- 'show system-information'

All this is currently not possible, and to archieve similar integration to our management infrastructure, we had to implement expect-like wrappers, that are much more complicated and time-consuming to build and slower to execute, and much more likely to fail because of changes in the output of future ZyNOS releases.

Best regards,
// Veit