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From Uwe Fischer <mistuwefisc...@web.de>
Subject Re: [Telnet] how to determine the prompt?
Date Tue, 03 Jun 2008 14:52:40 GMT
Hello Sebb,

maybe we misunderstood one another...
I was talking about the telnet client example, where the input stream is read as long as a
defined "prompt" character is found.
E.g., http://www.informit.com/guides/content.aspx?g=java&seqNum=40

In this example a command like 'ls -l > output.txt' would not be handled properly (of course
only if ">" is defined to be the prompt too). 

I hope I do not confuse you. Actually I'm just looking for another way to find out when a
command has been executed. Isn't the telnet standard offering anything like this? I mean,
does the client get some kind of status about the remote machine (something like "busy" or
"waiting for command" or similar).

Cheers,
Uwe




> On 03/06/2008, Uwe Fischer <mistuwefischer@web.de> wrote:
> > Hi Sebb,
> >
> >  your idea to change the prompt sounds good. However, how would I identify the very
first appearance of the prompt in order to change it? Also, is this (changing the prompt)
possible for Windows based telnet servers aswell?
> >
> 
> It's not the telnet server that provides the prompt, it's the
> application you are talking to, in that case presumably DOS.
> 
> You either need to know what the prompt is in advance, or wait for a timeout.
> 
> As I wrote before: how does a human know the system is ready for input?
> 
> >  Concerning your question, the problem with output redirection is that the program
would stop reading from the input stream, due to the appearance of ">" which would indicate
that the prompt has been reached. AFAIK.
> 
> That does not make sense to me.
> 
> If you telnet to a Unix system and issue the command:
> 
> ls -l >list.txt
> 
> the shell prompt will be issued as soon as the ls program has finished.
> 
> >  Cheers,
> >  Uwe
> >
> >
> >
> >  > -----Ursprüngliche Nachricht-----
> >  > Von: "sebb" <sebbaz@gmail.com>
> >  > Gesendet: 03.06.08 14:40:16
> >
> > > An: "Commons Users List" <user@commons.apache.org>
> >  > Betreff: Re: [Telnet] how to determine the prompt?
> >
> >
> >  > On 03/06/2008, Uwe Fischer <mistuwefischer@web.de> wrote:
> >  > > Hello Pierre,
> >  > >
> >  > >  thanks for your answer.
> >  > >  Yes, I did what you mention. But it's not "really" solving my issue.
The problem I face is that the devices I attach to can have the "#" or ">" characters maintained
in a user welcome messages when logging in. E.g., the following welcome message is displayed
when logging on to the device:
> >  > >  ############################################
> >  > >  Welcome at "hostname". In case of any issues contact Uwe
> >  > >  ############################################
> >  > >
> >  > >  How can one distinguish the "#" character when used in a comment and
when used to indicate the prompt?
> >  > >
> >  >
> >  > Can you set the prompt to a string that is not likely to be seen elsewhere?
> >  > Maybe even include a control character such as ^G (bell).
> >  >
> >  > If not, you are probably going to have to use timeouts to decide when
> >  > output has finished.
> >  >
> >  > >  Another problem could occur when somebody would redirect stdout of a
Unix system to a file, e.g.:
> >  > >  ls -l > output_list.txt
> >  > >
> >  > >  Any ideas?
> >  >
> >  > How would a human know when output has finished?
> >  >
> >  > >  Thanks and best regards,
> >  > >  Uwe
> >  > >
> >  > >
> >  > >  > -----Ursprüngliche Nachricht-----
> >  > >  > Von: "Pierre Brico" <pierre.brico@tsdsoftware.eu>
> >  > >  > Gesendet: 03.06.08 11:11:37
> >  > >  > An: "Commons Users List" <user@commons.apache.org>
> >  > >  > Betreff: Re: [Telnet] how to determine the prompt?
> >  > >
> >  > >
> >  > >
> >  > >  > Hello Uwe,
> >  > >  >
> >  > >  > Did you try to change the command prompt before executing the command.
You
> >  > >  > just should send commands to the shell like this:
> >  > >  >
> >  > >  > PS1="#>"
> >  > >  > export PS1
> >  > >  >
> >  > >  > And you will get the "#>" as prompt.
> >  > >  >
> >  > >  > Pierre
> >  > >  >
> >  > >  > On Tue, Jun 3, 2008 at 10:50 AM, Uwe Fischer <mistuwefischer@web.de>
wrote:
> >  > >  >
> >  > >  > > Hello all,
> >  > >  > >
> >  > >  > > I'm looking for a solution to a problem that bothers me for
quite some time
> >  > >  > > now and I hope somebody here can help me out.
> >  > >  > > I'm using the telnet api to connect to various systems, which
works fine.
> >  > >  > > The problem I face is, how can I determine that a command
has run to its
> >  > >  > > end if there is no static "prompt" character like "#" or ">",
but
> >  > >  > > dynamically changing prompt characters?
> >  > >  > >
> >  > >  > > I have read through the Telnet specification but couldn't
find anything
> >  > >  > > that deals with this kind of problem. But surely there must
be a solution to
> >  > >  > > this. I have found another thread in this mailing list concerning
a similar
> >  > >  > > issue, posted by: Anthony Webster Thu, 28 Feb 2008 10:54:35
GMT.
> >  > >  > > Unfortunately none has answered it yet.
> >  > >  > >
> >  > >  > > Thanking in advance,
> >  > >  > > U.F.
> >  > >  > >
> >  > >  > >
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