DataFlex

Receive from an SSH Channel Until Any Pattern Matches

Demonstrates the Chilkat Ssh.ChannelReceiveUntilMatchN method, which works like ChannelReceiveUntilMatch but returns when any pattern in a StringArray matches. The arguments are the channel number, the pattern array, the charset, and case sensitivity. The array must contain at least one element.

Important: Set the ReadTimeoutMs property before calling this method. It defaults to 0, meaning no limit, so without it the call waits forever if the received data never contains a match.

Background: A command often has more than one possible outcome, and your code should react to whichever occurs rather than hang waiting for one specific string. A common non-interactive pattern is to have the command print one marker on success and a different marker on failure, then match on the set. (With no PTY there is no shell prompt to match against, so markers you emit yourself are the dependable signal.) The first matching content in the stream wins; array order does not override an earlier token. Empty elements are ignored and duplicates are allowed.

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Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iSshPort
    String sPassword
    Integer iChannelNum
    Variant vPatterns
    Handle hoPatterns
    Boolean iCaseSensitive
    String sOutput
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  Demonstrates the Ssh.ChannelReceiveUntilMatchN method, which receives text until ANY pattern
    //  in a StringArray is matched.  The 1st argument is the channel number, the 2nd is the array of
    //  patterns, the 3rd is the charset, and the 4th selects case-sensitive matching.

    Get Create (RefClass(cComChilkatSsh)) To hoSsh
    If (Not(IsComObjectCreated(hoSsh))) Begin
        Send CreateComObject of hoSsh
    End

    Move 22 To iSshPort
    Get ComConnect Of hoSsh "ssh.example.com" iSshPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSsh "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComOpenSessionChannel Of hoSsh To iChannelNum
    If (iChannelNum < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Get ComSendReqShell Of hoSsh iChannelNum To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  There is no prompt to match on.  Instead, run a command that prints one marker on success
    //  and a different marker on failure, then wait for whichever appears first.
    Get ComChannelSendString Of hoSsh iChannelNum "test -f /etc/hosts && echo OK_MARKER || echo ERR_MARKER" + (character(10)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComCkStringArray)) To hoPatterns
    If (Not(IsComObjectCreated(hoPatterns))) Begin
        Send CreateComObject of hoPatterns
    End
    Get ComAppend Of hoPatterns "OK_MARKER" To iSuccess
    Get ComAppend Of hoPatterns "ERR_MARKER" To iSuccess

    //  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.
    Set ComReadTimeoutMs Of hoSsh To 15000

    Move False To iCaseSensitive
    Get pvComObject of hoPatterns to vPatterns
    Get ComChannelReceiveUntilMatchN Of hoSsh iChannelNum vPatterns "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sOutput
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sOutput

    Send ComDisconnect To hoSsh


End_Procedure