Where does the "prompt come from"

[Niclas Bäckman C (LI/EAB)]

Hi Damien !
Thanks for your feedback !
We have implemented a secure command line interface api that wants to perform "normal" shell
operations, but from an application. 
That's why I don't want to add a new subsystem.
I just want to run for instance scripts, towards a secured remote host. But the data that is passed
to the socket doesn't include the prompt itself, like '>'. The socket is a redirekt from the client's
stdout/stderr.
If I use a standard client like OpenSSH the client echoes back the prompt after a command is executed,
but in my scenarion it's lost and never written to stdout/stderr(my socket).
Does the SSH client remove the prompt in some way before data is passed to stdout/stderr ??
Many thanks in advance !
/Niclas


-----Original Message-----
From: Damien Miller [mailto:djm at mindrot.org]
Sent: den 25 mars 2004 00:56
To: Niclas Bäckman C (LI/EAB)
Cc: 'openssh-unix-dev at mindrot.org'
Subject: Re: Where does the "prompt come from"


Niclas Bäckman C (LI/EAB) wrote:

> Hi All !
> I have a little question about the shell that is run when establishing a
> connection towards an SSH server.
> The client(OpenSSH) displays a prompt(as usual) when a command is executed,
> but my question is, where does the prompt come from.
> Is it sent by the remote shell or is it handled in the client ??
> 
> The reason I ask is that we have developed a product that redirects
> stdin/stdout/stderr from the ssh binary to a socket, and we then
> perform socket read/writes directly into the ssh tunnel. But when i perform
> a command, the prompt is never read up from the server.
> So it's difficult to know when a remote script is finished. Using the same
> solution but towards a telnet server always results in a prompt
> back to the client.

The prompt comes from the shell that the server executes.

If you want to use OpenSSH as a transport, you should probably invent a
little protocol and implement it as a subsystem. sftp does this.

-d

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