Delphi ActiveX

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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var
success: Integer;
ssh: TChilkatSsh;
sshPort: Integer;
password: WideString;
channelNum: Integer;

begin
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.

ssh := TChilkatSsh.Create(Self);

sshPort := 22;
success := ssh.Connect('ssh.example.com',sshPort);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  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.
password := 'mySshPassword';

success := ssh.AuthenticatePw('mySshLogin',password);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  Open a session channel.  A negative return value indicates failure.
channelNum := ssh.OpenSessionChannel();
if (channelNum < 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  Start a long-running command.
success := ssh.SendReqExec(channelNum,'sleep 60');
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  Send an interrupt signal to the remote process.  The name omits the "SIG" prefix.
success := ssh.SendReqSignal(channelNum,'INT');
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Signal sent.');

ssh.Disconnect();