Xojo Plugin

Start a Remote Shell with QuickShell

Demonstrates the Chilkat Ssh.QuickShell method, which starts a remote shell using the simplified sequence OpenSessionChannel → SendReqPty → SendReqShell. It takes no arguments and returns the shell channel number, or -1 on failure. The default PTY size is 80 columns by 24 rows.

Background: Note that QuickShell does allocate a PTY, so unlike a bare SendReqShell the remote shell runs interactively: it prints a command prompt, echoes the commands you send, and runs interactive login scripts. That is convenient for terminal-style work but means the output contains prompts and echoed input that scripted parsing must tolerate. The method returns as soon as the shell request is accepted — it does not consume the initial login text or prompt, so read and discard that before relying on command output.

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Dim success As Boolean
success = False

//  Demonstrates the Ssh.QuickShell method, which starts a remote shell using the simplified
//  sequence OpenSessionChannel, SendReqPty, and SendReqShell.  It takes no arguments and returns
//  the shell channel number, or -1 on failure.  The default PTY size is 80 columns by 24 rows.

Dim ssh As New Chilkat.Ssh

Dim sshPort As Int32
sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
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 = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  Start the shell.  Note that QuickShell allocates a PTY, so the remote shell runs
//  interactively: it prints a command prompt and echoes the commands that are sent to it.
Dim channelNum As Int32
channelNum = ssh.QuickShell()
If (channelNum < 0) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

//  QuickShell returns as soon as the shell request is accepted -- it does not wait for or
//  consume the initial login text or prompt.
success = ssh.ChannelSendString(channelNum,"uname -a; echo DONE_MARKER" + EndOfLine.Unix,"utf-8")
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
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
caseSensitive = False
success = ssh.ChannelReceiveUntilMatch(channelNum,"DONE_MARKER","utf-8",caseSensitive)
If (success = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

Dim output As String
output = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = False) Then
    System.DebugLog(ssh.LastErrorText)
    Return
End If

System.DebugLog(output)

ssh.Disconnect