Get Received SSH Text Up To a Substring

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Demonstrates the Chilkat Ssh.GetReceivedTextS method, which searches the receive buffer for a literal, case-sensitive substring. The arguments are the channel number, the substring, and the charset. If found, everything through and including the first occurrence is returned and removed; if not found, an empty string is returned successfully and the buffer is left unchanged.

Dim success As Boolean = False

'  Demonstrates the Ssh.GetReceivedTextS method, which searches the receive buffer for a literal
'  substring.  The 1st argument is the channel number, the 2nd is the substring, and the 3rd is
'  the charset.  If found, everything through and including the first occurrence is returned and
'  removed from the buffer.

Dim ssh As New Chilkat.Ssh

Dim sshPort As Integer = 22
success = ssh.Connect("ssh.example.com",sshPort)
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


'  Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
'  raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
'  echo typed commands back, and skips interactive login scripts.  The output is therefore
'  clean and easily parseable -- but because no prompt is ever sent, code must not wait for
'  one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
success = ssh.SendReqShell(channelNum)
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


success = ssh.ChannelSendString(channelNum,"echo BEGIN; ls /tmp; echo END_MARKER" & vbLf,"utf-8")
If (success = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


Dim pollTimeoutMs As Integer = 1000
Dim result As Integer = ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs)
If (result = -1) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Return everything up through the marker.  If the marker is not present, an empty string is
'  returned successfully and the buffer is left unchanged.
Dim upToMarker As String = ssh.GetReceivedTextS(channelNum,"END_MARKER","utf-8")
If (ssh.LastMethodSuccess = False) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(upToMarker)

ssh.Disconnect()