With the command sub-protocol (which I'm calling it because I don't remember what it is otherwise called) a client (fabric, ssh, etc) will be told the return code of a command when it finishes executing on the remote machine.
With the shell sub-protocol, you are told the return code of the shell, when the shell session ends. Shell sessions usually end “well” even if all the commands executed through it has failed. Shells also typically wait for more input when they've finished running a command, and they only notify you of this by printing a dynamically configurable string that typically doesn't end with a line break. That's why tools like fabric prefer to use the command sub-protocol. I don't know of any good work around to this. Chris On 10 Apr 2013, at 19:04, Zhigang Wang <[email protected]> wrote: > On Wed, Apr 10, 2013 at 9:49 AM, Chris Vest <[email protected]> wrote: >> So you say this works: >> echo "<cmd>" | ssh user@host:port > > yes > >> Does this work? >> ssh user@host:port "<cmd>" > > no > >> >> Fabric (assuming my info is current) uses the command sub-protocol of ssh, >> not the shell sub-protocol, which I'm guessing is what happens when you pipe >> to ssh. > > Seems we are tracking down to the point. Will check what is the difference > between the two. If anyone has a workaround for fabric to use "shell > sub-protocol"? > > Thanks, > > Zhigang > >> Chris >> >> On 10/04/2013, at 16.51, Zhigang Wang <[email protected]> wrote: >> >>> Thanks very much. However, it doesn't work. >>> >>> I think this issue may live in the paramiko side: don't know anyone >>> familiar with the difference between: >>> >>> 1. ssh user@host:port <cmd> >>> >>> 2. echo "<cmd>" | ssh user@host:port >>> >>> The second one works. So maybe we can emulate that behavior in >>> paramiko/fabric. >>> >>> Thanks, >>> >>> Zhigang >>> >>> >>> >>> On Tue, Apr 9, 2013 at 9:52 PM, Jeff Forcier <[email protected]> wrote: >>>> Pro tip: >>>> >>>> * Read up on what ssh -T does (it disables allocation of a remote pty) >>>> * Search Fabric docs for "pty" >>>> * Find out you can set env.always_use_pty=False to disable use of a remote >>>> pty >>>> * Hopefully discover that this fixes the problem (?) >>>> >>>> >>>> On Tue, Apr 9, 2013 at 7:16 PM, Zhigang Wang <[email protected]> wrote: >>>> > Thanks. >>>> > >>>> > Currently I hit this: >>>> > http://net-ssh.lighthouseapp.com/projects/36253/tickets/32-sun-ilom-wont-accept-commands-even-after-successful-login >>>> > >>>> > Maybe a ILOM bug, but they have workaround: >>>> > >>>> > Doesnt' work: >>>> > >>>> > $ ssh -t root@ca-dev33m "show /SYS" >>>> > >>>> > Warning: Permanently added 'ca-dev33m,10.211.2.238' (RSA) to the list of >>>> > known hosts. >>>> > Password: >>>> > shell: Invalid credentials >>>> > >>>> > >>>> > Connection to ca-dev33m closed. >>>> > >>>> > Works: >>>> > >>>> > $ echo "show /SYS" | ssh -T root@ca-dev33m >>>> > >>>> > How to clone the same behavior in fabric? >>>> > >>>> > Using our fabric: >>>> > >>>> > # python ilom.py -s root@ca-dev33m -p changeme >>>> > /usr/lib64/python2.6/site-packages/Crypto/Util/number.py:57: >>>> > PowmInsecureWarning: Not using mpz_powm_sec. You should rebuild using >>>> > libgmp >= 5 to avoid timing attack vulnerability. >>>> > _warn("Not using mpz_powm_sec. You should rebuild using libgmp >= 5 to >>>> > avoid timing attack vulnerability.", PowmInsecureWarning) >>>> > [root@ca-dev33m] Executing task 'ilom_get_mac' >>>> > [root@ca-dev33m] run: show /System ilom_mac_address >>>> > INFO:paramiko.transport:Connected (version 2.0, client OpenSSH_5.1) >>>> > INFO:paramiko.transport:Authentication (keyboard-interactive) successful! >>>> > INFO:paramiko.transport:Secsh channel 1 opened. >>>> > [root@ca-dev33m] out: shell: Invalid credentials >>>> > [root@ca-dev33m] out: >>>> > [root@ca-dev33m] out: >>>> > [root@ca-dev33m] out: >>>> > >>>> > Disconnecting from ca-dev33m... done. >>>> > shell: Invalid credentials >>>> > >>>> > >>>> > From here: >>>> > https://groups.google.com/group/mailing.unix.openssh-dev/tree/browse_frm/month/2009-07?_done=%2Fgroup%2Fmailing.unix.openssh-dev%2Fbrowse_frm%2Fmonth%2F2009-07%3F&; >>>> > >>>> > It may related to the buffersize? How can I enlarge the buffersize for >>>> > fabric? >>>> > >>>> > I tried env.linewise=True, it doesn't help. >>>> > >>>> > I will continue debugging on it. >>>> > >>>> > Thanks, >>>> > >>>> > Zhigang >>>> > >>>> > >>>> > On Tue, Apr 9, 2013 at 6:55 PM, Jeff Forcier <[email protected]> wrote: >>>> >> >>>> >> Try setting env.use_shell = False: >>>> >> >>>> >> http://docs.fabfile.org/en/1.6/usage/env.html#use-shell >>>> >> >>>> >> On Tue, Apr 9, 2013 at 6:40 PM, Zhigang Wang <[email protected]> wrote: >>>> >> > Hi Jeff and all, >>>> >> > >>>> >> > I want to use fabric for ilom, a ssh configuration interface. >>>> >> > Currently >>>> >> > it >>>> >> > doesn't work because the ilom system doesn't have a shell there. How >>>> >> > can >>>> >> > set >>>> >> > env.shell to none? Or is it supported? >>>> >> > >>>> >> > The ilom shell: >>>> >> > >>>> >> > $ ssh root@ca-dev33m >>>> >> > Warning: Permanently added 'ca-dev33m,10.211.2.238' (RSA) to the list >>>> >> > of >>>> >> > known hosts. >>>> >> > Password: >>>> >> > >>>> >> > Oracle(R) Integrated Lights Out Manager >>>> >> > >>>> >> > Version 3.1.2.10 r74387 >>>> >> > >>>> >> > Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. >>>> >> > >>>> >> > Warning: password is set to factory default. >>>> >> > >>>> >> > -> help >>>> >> > The help command is used to view information about commands and >>>> >> > targets >>>> >> > >>>> >> > Usage: help [-format wrap|nowrap] [-o|-output terse|verbose] >>>> >> > [<command>|legal|targets|<target>|<target> <property>] >>>> >> > >>>> >> > Special characters used in the help command are >>>> >> > [] encloses optional keywords or options >>>> >> > <> encloses a description of the keyword >>>> >> > (If <> is not present, an actual keyword is indicated) >>>> >> > | indicates a choice of keywords or options >>>> >> > >>>> >> > help <target> displays description if this target and its >>>> >> > properties >>>> >> > help <target> <property> displays description of this property of >>>> >> > this >>>> >> > target >>>> >> > help targets displays a list of targets >>>> >> > help legal displays the product legal notice >>>> >> > >>>> >> > Commands are: >>>> >> > cd >>>> >> > create >>>> >> > delete >>>> >> > dump >>>> >> > exit >>>> >> > help >>>> >> > load >>>> >> > reset >>>> >> > set >>>> >> > show >>>> >> > start >>>> >> > stop >>>> >> > version >>>> >> > >>>> >> > -> sh >>>> >> > Invalid command 'sh' - type help for a list of commands. >>>> >> > >>>> >> > -> bash >>>> >> > Invalid command 'bash' - type help for a list of commands. >>>> >> > >>>> >> > Thanks, >>>> >> > >>>> >> > Zhigang >>>> >> >>>> >> >>>> >> >>>> >> -- >>>> >> Jeff Forcier >>>> >> Unix sysadmin; Python/Ruby engineer >>>> >> http://bitprophet.org >>>> > >>>> > >>>> >>>> >>>> >>>> -- >>>> Jeff Forcier >>>> Unix sysadmin; Python/Ruby engineer >>>> http://bitprophet.org >>> >> >>> _______________________________________________ >>> Fab-user mailing list >>> [email protected] >>> https://lists.nongnu.org/mailman/listinfo/fab-user >
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