SQL Server

Send a Signal to a Remote SSH Process

Demonstrates the Chilkat Ssh.SendReqSignal method, which requests delivery of a signal to the remote process running on a channel. The first argument is the channel number and the second is the signal name. Send it after the process has started.

Background: This is the SSH equivalent of pressing Ctrl+C or running kill — it lets a client interrupt or terminate a long-running remote command without tearing down the connection. Signal names are given without the SIG prefix (INT, TERM, KILL, and so on). Note that some servers, including common OpenSSH builds, do not implement signal delivery.

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-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the Ssh.SendReqSignal method, which requests delivery of a signal to the remote
    --  process running on a channel.  The 1st argument is the channel number and the 2nd is the
    --  signal name.  Send it after the process has started.

    DECLARE @ssh int
    EXEC @hr = sp_OACreate 'Chilkat.Ssh', @ssh OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @sshPort int
    SELECT @sshPort = 22
    EXEC sp_OAMethod @ssh, 'Connect', @success OUT, 'ssh.example.com', @sshPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        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.
    DECLARE @password nvarchar(4000)
    SELECT @password = 'mySshPassword'

    EXEC sp_OAMethod @ssh, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Open a session channel.  A negative return value indicates failure.
    DECLARE @channelNum int
    EXEC sp_OAMethod @ssh, 'OpenSessionChannel', @channelNum OUT
    IF @channelNum < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Start a long-running command.
    EXEC sp_OAMethod @ssh, 'SendReqExec', @success OUT, @channelNum, 'sleep 60'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Send an interrupt signal to the remote process.  The name omits the "SIG" prefix.
    EXEC sp_OAMethod @ssh, 'SendReqSignal', @success OUT, @channelNum, 'INT'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    PRINT 'Signal sent.'

    EXEC sp_OAMethod @ssh, 'Disconnect', NULL

    EXEC @hr = sp_OADestroy @ssh


END
GO