This isn't a limitation of Fabric itself, but is specific to how SSH works
- to encapsulate each command as a discrete result of output, exit code,
etc, one must use a distinct command-execution call to the SSH daemon for
each command. (This is in the FAQ as
http://www.fabfile.org/faq.html#my-cd-workon-export-etc-calls-don-t-seem-to-work
though the title is a bit specific.)
If your use case can deal with that limitation - i.e. if your intent is to
just run the commands and not do programmatic things with its output or
exit codes partway through - you could try submitting a multiline string as
the argument to `run`, e.g.:
run("""screen-length disable
display current-configuration""")
(Or use '\n', etc.)
How well that will work depends on how your switch's shell behaves with
that style of 'batched' input.
If the switch's shell supports any sort of single-line continuations (like
'&&' or ';' in typical Unix shells) that's another approach. You could
leverage the 'with prefix()' feature of Fabric then too (
http://docs.fabfile.org/en/latest/api/core/context_managers.html#fabric.context_managers.prefix
).
Good luck,
Jeff
On Fri, Nov 18, 2016 at 7:00 AM, Brandon Whaley <[email protected]> wrote:
> You may be able to use the underlying paramiko library that Fabric itself
> relies on, but I don't have any personal experience with it.
>
> On Fri, Nov 18, 2016 at 3:57 AM <[email protected]> wrote:
>
>> Hello Brandon,
>>
>>
>> (sorry for the direct reply, I didn't notice that the To: wasn't to the
>> ML)
>>
>> Thank you for your reply.
>> Unfortunately sending newlines (or carriage return) between two commands
>> inside one run() didn't help.
>> Since between each run() I'm loosing my execution session, are you aware
>> about another ssh module for Python that doesn't have this behaviour?
>>
>> Many Thanks,
>>
>> Regards,
>>
>>
>> Alexandre
>>
>>
>> ----- Original Message -----
>> From: "Brandon Whaley" <[email protected]>
>> To: "a hocquel" <[email protected]>, [email protected]
>> Sent: Thursday, 17 November, 2016 7:54:24 PM
>> Subject: Re: [Fab-user] HP switches and run() received nonzero return
>> code -1 while executing
>>
>>
>> Fabric was written with accessing *nix based servers in mind, so some
>> things it does don't work correctly with non-standard ssh implementations.
>> I'm not sure if HP is returning the -1 code or if Fabric is not getting one
>> at all and as such returns -1 as an error value. Either way, it sounds like
>> you'll always need to use warn_only=True for this device.
>>
>>
>> One of the biggest differences between an interactive ssh session and
>> Fabric is that when you use run(), while only one ssh connection is ever
>> made, a new command execution session is initiated over that connection for
>> each operation. That means things like environment variables are "fresh" at
>> every call to run(). I suspect this is why your "screen-length disable"
>> command does not take effect, since HP's docs state "Note that this command
>> is applicable to the current user only and when a user re-logs in, the
>> settings restore to the system default."
>>
>>
>> Have you tried sending newlines between two commands in the same run()?
>> That might be a workaround for you if the switch allows it.
>>
>>
>> On Thu, Nov 17, 2016 at 10:43 AM < [email protected] > wrote:
>>
>>
>> Hello,
>>
>>
>> I'm new here, and before writing this email I searched on the archives
>> without success, so please excuse me if this question was already asked.
>>
>> I'm trying to "display current-configuration" through ssh on HP 5820
>> series switches with this piece of code :
>>
>> from fabric.api import *
>>
>> env.user = 'toto'
>> env.hosts = ['192.168.72.10']
>> def displaycurr():
>> with settings(hide('warnings'), warn_only=True):
>> # below command is normally used to prevent the "more"
>> run('screen-length disable ', shell=False)
>> run('display current-configuration ', shell=False)
>>
>>
>> As written in the email's subject, every ran command returns a nonzero
>> code, implying that even if I forced the "keep running" with the
>> warn_only=True option, after each run command the ssh session is exited.
>> Therefore I lost the first command advantage and then I got the "more"
>> during the second.
>>
>> Same code (without warn_only) and the right Cisco commands does work well
>> on Cisco switches.
>>
>>
>> By any chance, is there someone that experienced the same issue (not
>> necessarily with HP switches) and managed to keep the ssh session opened
>> between both commands?
>>
>>
>> Many Thanks,
>>
>> Regards,
>>
>>
>> Alexandre
>>
>>
>>
>>
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>>
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>
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>
--
Jeff Forcier
Unix sysadmin; Python engineer
http://bitprophet.org
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