SSH ChannelReceiveUntilMatchN (Match Any of Several Prompts)

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Demonstrates ChannelReceiveUntilMatchN, which receives until any one of several patterns is matched. This is useful when driving an interactive session where the shell prompt differs from device to device.

Note: This example deliberately requests a PTY. Matching a shell prompt only works in an interactive session — without a PTY the shell runs non-interactively and never prints a prompt at all. For scripted use, omit the PTY and match on a marker your own command echoes.

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  Demonstrates ChannelReceiveUntilMatchN, which receives until ANY one of several patterns is
'  matched.  This is useful when driving an interactive session where the shell prompt varies
'  from device to device.
'  
'  Note: This example deliberately DOES request a PTY.  Matching a shell prompt only works in an
'  interactive session -- without a PTY the shell runs non-interactively and never prints a
'  prompt at all.  For scripted use where no prompt is needed, omit the PTY and match on a
'  marker your own command echoes instead.

Dim ssh As New Chilkat.Ssh

'  The remote shell prompt may be any of these, depending on the device.
Dim saPrompts As New Chilkat.StringArray
saPrompts.Append("~$")
saPrompts.Append("mars#")
saPrompts.Append("jupiter%")
saPrompts.Append("chilkat$")
saPrompts.Append("admin>")

Dim hostname As String = "ssh.example.com"
Dim port As Integer = 22
success = ssh.Connect(hostname,port)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
Dim password As String = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


Dim channelNum As Integer = ssh.OpenSessionChannel()
If (channelNum < 0) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Request a pseudo-terminal so the shell runs interactively and prints prompts.  A "dumb"
'  terminal is used so that ANSI escape sequences are not mixed into the output.
Dim termType As String = "dumb"
Dim widthInChars As Integer = 120
Dim heightInChars As Integer = 40
Dim pixWidth As Integer = 0
Dim pixHeight As Integer = 0
success = ssh.SendReqPty(channelNum,termType,widthInChars,heightInChars,pixWidth,pixHeight)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


success = ssh.SendReqShell(channelNum)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
'  which means no limit -- without it, this call waits forever if the received data never
'  contains a match.
ssh.ReadTimeoutMs = 15000

Dim caseSensitive As Boolean = True

'  Read the initial login text up to the first prompt.
success = ssh.ChannelReceiveUntilMatchN(channelNum,saPrompts,"utf-8",caseSensitive)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


Dim cmdOutput As String = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

'  ---- 1st command ----
success = ssh.ChannelSendString(channelNum,"cd /tmp" & vbLf,"utf-8")
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


success = ssh.ChannelReceiveUntilMatchN(channelNum,saPrompts,"utf-8",caseSensitive)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Retrieving the text also clears the receive buffer, which matters: if a prompt were left
'  buffered, the next receive would match it immediately and return the wrong output.
cmdOutput = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

'  ---- 2nd command ----
success = ssh.ChannelSendString(channelNum,"ls" & vbLf,"utf-8")
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


success = ssh.ChannelReceiveUntilMatchN(channelNum,saPrompts,"utf-8",caseSensitive)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


cmdOutput = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

'  Finish the session.
success = ssh.ChannelSendEof(channelNum)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


success = ssh.ChannelReceiveToClose(channelNum)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


cmdOutput = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

ssh.Disconnect()