Visual Basic 6.0

Collect Completed SSH Commands with QuickCmdCheck

Demonstrates the Chilkat Ssh.QuickCmdCheck method, which waits for any command started by QuickCmdSend to complete. The only argument is the poll timeout in milliseconds; 0 performs a nonblocking check. It returns the channel number of a completed command, -1 when commands are still pending but none finished before the timeout, or -2 when no quick commands remain or an error occurred.

Background: This is the collection half of the concurrent pattern. Each completed channel is reported only once, so looping until -2 drains every outstanding command exactly once. Distinguish the two negative values carefully: -1 simply means "still working, ask again," while -2 means there is nothing left to wait for — or that the connection failed, so check LastErrorText when the distinction matters. Manually opened exec channels are not reported here.

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Dim success As Long
success = 0

'  Demonstrates the Ssh.QuickCmdCheck method, which waits for any command started by
'  QuickCmdSend to complete.  The only argument is the poll timeout in milliseconds; 0 performs
'  a nonblocking check.

Dim ssh As New ChilkatSsh

Dim sshPort As Long
sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
If (success = 0) Then
    Debug.Print 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
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  Start two commands that will finish at different times.
Dim channel1 As Long
channel1 = ssh.QuickCmdSend("sleep 2; echo first done")
If (channel1 < 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

Dim channel2 As Long
channel2 = ssh.QuickCmdSend("echo second done")
If (channel2 < 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  Collect the results as they complete.  The return value is the channel number of a completed
'  command, -1 if commands are still pending but none finished before the timeout, or -2 when
'  no quick commands remain (or an error occurred).
Dim pollTimeoutMs As Long
pollTimeoutMs = 5000
Dim completedChannel As Long
completedChannel = ssh.QuickCmdCheck(pollTimeoutMs)
Do While completedChannel <> -2
    If (completedChannel >= 0) Then
        Dim output As String
        output = ssh.GetReceivedText(completedChannel,"utf-8")
        If (ssh.LastMethodSuccess = 0) Then
            Debug.Print ssh.LastErrorText
            Exit Sub
        End If

        Debug.Print "Channel " & completedChannel & " finished: " & output
    End If

    If (completedChannel = -1) Then
        Debug.Print "Still waiting for a command to finish..."
    End If

    completedChannel = ssh.QuickCmdCheck(pollTimeoutMs)
Loop

Debug.Print "All quick commands have been collected."

ssh.Disconnect