Re: Multiple calls to channel_request_exec()

[Stephan Kountso <steplg@xxxxxxxxx>]

>
> So basically if I use channel_request_shell() then the environment on
> the server will be retained between subsequent calls to
> channel_request_shell() ?
>
When you requesting shell, then server actually starts shell for you. And
you program will get all text you see, when you are connecting to server
with openssh or putty client for example. And yes, you'll receive all
prompts and duplication commands you input. And no, you won't be noticed
when one program stops execution and shell is waiting for next command.

>
> I don't fully understand the statement(s) about not being able to parse
> the $ or # prompts (or in the previous email; "you must know shell
> prompt before you begin communication". Is this because the shell prompt
> is included in the contents of channel_read() ?
>
Yes. And because on different machines you may have (actually, you really
will have) different prompts. So, there is no way to figure out current
prompt in runtime.


> Thanks, Mark
>
> On Thu, 2010-02-25 at 10:19 +0100, Aris Adamantiadis wrote:
> > Hi,
> >
> > Indeed, you can execute only one command using channel_request_exec. But
> > you may either
> >
> > -execute several commands
> > -start a scripting language
> > example:
> > channel_request_exec(channel,"cd /tmp; mkdir mytest; cd mytest; touch
> > mytest");
> > This will be executed as only one shell command. Another solution is
> > // Do NOT put the channel into interactive mode/pty
> > channel_request_shell(channel);
> > channel_write(channel,"cd /tmp ; echo OK");
> > channel_read(...)
> > channel_write(channel,"mkdir mytest ; echo OK");
> > ...
> > basicaly that's like a shell script. Do not expect being able to parse
> > the "#" or "$" prompts, it won't work...
> >
> > hope this helps.
> >
> > Aris
> >
> > Mark Hessling a écrit :
> > > I'm looking at libssh to enable the replacement of an existing
> > > application that uses raw sockets to control a telnet session. In
> future
> > > the connection must be done using ssh.
> > >
> > > I tried modifying examples/exec.c and duplicated the block of code that
> > > calls channel_request_exec() to execute "ps aux" and to read the
> output.
> > > I simply added a call to channel_request_exec() to execute "ls -l", but
> > > I received an error: "Channel exec request failed".
> > >
> > > Should I be able to with libssh, execute a shell command on the remote
> > > host, read its output and execute another shell command and read its
> > > output?
> > >
> > >>From my reading of the documentation it appears that each call to
> > > channel_request_exec() spawns another shell on the remote server, so if
> > > I wanted to execute the following on the remote server:
> > > "cd tmp"
> > > "./run_my_command"
> > > then the second command would not be executed in the "tmp" directory.
> > >
> > > Does libssh then need a "changedirectory" function similar to the one
> > > that sets environment variables?
> > >
> > > Thanks in advance for your responses.
> > >
> >
> >
>
>
> --
>
> * Mark Hessling, mark@xxxxxxxx http://www.rexx.org/
> * Author of THE, a Free XEDIT/KEDIT editor, Rexx/SQL, Rexx/CURL,  etc.
> * Maintainer of Regina Rexx interpreter and Rexx/Tk
> * Use Rexx? join the Rexx Language Association: http://www.rexxla.org/
>
>
>


-- 
Best Wishes,
Stephan Kountso aka StepLg