Vista Tutorial - StdOut and StdErr reading...

Hello!

I'm working on a script to automate SFTP operations (using a text-
based sftp client).
My idea is to use the Exec() method to run the client, send commands
via StdIn and receive output via StdOut and StdErr.

The problem is that when I try to read buffers using ReadAll or
AtEndOfStream, those methods are blocking and never ends... for StdOut
I was able to find a condiction (when I read "sftp>" from the buffer)
to end reading, but for StdErr? Is there a way to know how many chars
are in the buffer to use the Read(n) method which is not blocking?

Thanks!

---
Dim objFSO, objShell, objCmd

Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objShell = CreateObject("WScript.Shell")
Set objCmd = objShell.Exec("sftp -F /home/sshuser/.ssh/ssh_config
sshuser@xxxxxx")

WScript.Echo ReadOutput(objCmd.StdOut)

objCmd.StdIn.WriteLine("pwd")
WScript.Echo ReadOutput(objCmd.StdOut)

objCmd.StdIn.WriteLine("ls")
WScript.Echo ReadOutput(objCmd.StdOut)

objCmd.StdIn.WriteLine("ls download.ok")
WScript.Echo ReadOutput(objCmd.StdOut)
WScript.Echo objCmd.StdErr.ReadAll ' <-- blocking!!!

WScript.Echo "close"
objCmd.StdIn.WriteLine("close")


Function ReadOutput(stream)

Dim strOut

Do
If Not stream.AtEndOfStream Then
strOut = strOut & stream.Read(1)
If Right(strOut, 5) = "sftp>" Then
strOut = Left(strOut, Len(strOut) - 5)
Exit Do
End If
End If
Loop

ReadOutput = strOut

End Function

lucadentella@xxxxxx wrote:hi Lucadentella,

I can't say exactly what is going wrong with your
script, but I can say that stdin/out can get tricky.

In some cases a careful use of "sleep" can help,
that is, by allowing time for things to develop.

For example, if you run you app "manually", and
see some delays as it is working, then when you
script it, that would be the place (or places) to
insert your delay(s).

If nothing else, without any "sleep" calls (analagous
to vb's DoEvents) you may be "hogging-the-cpu", and
not allowing your other app (which is doing the "real
work") to have a chance at getting the cpu so it can
get going...

The following snippet of code did not work for me
until after I inserted the "sleep".

--- <code> ---
Set oExec = WshShell.Exec(sScriptFolder & "testCase.bat")
sInput = ""

Do While True

If Not oExec.StdOut.AtEndOfStream Then
' sInput = sInput & oExec.StdOut.Read(1) ' read one character
sInput = sInput & oExec.StdOut.ReadLine & vbCrLf
' WScript.Echo sInput
If InStr(sInput, "Press any key") <> 0 Then Exit Do
End If
WScript.Sleep 10
Loop

oExec.StdIn.Write vbCrLf
--- </code> ---

cheers, jw
____________________________________________________________

You got questions? WE GOT ANSWERS!!! ..(but, no guarantee
the answers will be applicable to the questions)

<lucadentella@xxxxxx> wrote in message
news:80ae145e-64b5-4a22-babb-4da21a080ccf@xxxxxxYour ReadOutput function is flawed: It will loop forever unless it
finds the string "sftp" in the stream. Try this instead:
Function ReadOutput(stream)
Do
If Not stream.AtEndOfStream Then
strOut = strOut & stream.Read(1)
If Right(strOut, 5) = "sftp>" Then
strOut = Left(strOut, Len(strOut) - 5)
Exit Do
End If
Else
Exit Do
End If
Loop
ReadOutput = strOut
End Function

Hello!

Thanks for your answers... the problem I'm facing is about StdErr: I
need a way to read exaclty all the characters in that moment are in
that buffer, but ReadAll, AtEndOfStream are blocking. Is there a way
to count the chars so I can use Read(n)?

Il giorno Thu, 7 Aug 2008 01:50:50 -0700 (PDT), lucadentella@xxxxxx ha scritto:Hello,
I dropped a project I was working on (reading e-mails using vbs as an interface for
netcat) because I had some problems as yours.
Can you confirm I can read a stream before it is closed and while the output is still
being writing?
Thank you.
Giovanni.

--
Giovanni Cenati (Bergamo, Italy)
Write to "Reventlov" at katamail com
http://digilander.libero.it/Cenati (Esempi e programmi in VbScript)
--