Visual FoxPro

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 lnSuccess
LOCAL loSsh
LOCAL lnSshPort
LOCAL lcPassword
LOCAL lnChannelNum
LOCAL lnCaseSensitive
LOCAL lcOutput

lnSuccess = 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.

loSsh = CreateObject('Chilkat.Ssh')

lnSshPort = 22
lnSuccess = loSsh.Connect("ssh.example.com",lnSshPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
lcPassword = "mySshPassword"

lnSuccess = loSsh.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
lnChannelNum = loSsh.QuickShell()
IF (lnChannelNum < 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  QuickShell returns as soon as the shell request is accepted -- it does not wait for or
*  consume the initial login text or prompt.
lnSuccess = loSsh.ChannelSendString(lnChannelNum,"uname -a; echo DONE_MARKER" + CHR(10),"utf-8")
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
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.
loSsh.ReadTimeoutMs = 15000

lnCaseSensitive = 0
lnSuccess = loSsh.ChannelReceiveUntilMatch(lnChannelNum,"DONE_MARKER","utf-8",lnCaseSensitive)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

lcOutput = loSsh.GetReceivedText(lnChannelNum,"utf-8")
IF (loSsh.LastMethodSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

? lcOutput

loSsh.Disconnect()

RELEASE loSsh