Xbase++

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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LOCAL nSuccess
LOCAL oSsh
LOCAL nSshPort
LOCAL cPassword
LOCAL nChannelNum
LOCAL nCaseSensitive
LOCAL cOutput

nSuccess := 0

//  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.

oSsh := CreateObject("Chilkat.Ssh")

nSshPort := 22
nSuccess := oSsh:Connect("ssh.example.com", nSshPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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.
cPassword := "mySshPassword"

nSuccess := oSsh:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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.
nChannelNum := oSsh:QuickShell()
IF (nChannelNum < 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  QuickShell returns as soon as the shell request is accepted -- it does not wait for or
//  consume the initial login text or prompt.
nSuccess := oSsh:ChannelSendString(nChannelNum, "uname -a; echo DONE_MARKER" + Chr(10), "utf-8")
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  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.
oSsh:ReadTimeoutMs := 15000

nCaseSensitive := 0
nSuccess := oSsh:ChannelReceiveUntilMatch(nChannelNum, "DONE_MARKER", "utf-8", nCaseSensitive)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

cOutput := oSsh:GetReceivedText(nChannelNum, "utf-8")
IF (oSsh:LastMethodSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

? cOutput

oSsh:Disconnect()

oSsh:destroy()