Pascal (Lazarus/Delphi)

Get Text Received on the SSH stderr Buffer

Demonstrates the Chilkat Ssh.GetReceivedStderrText method, which decodes and returns the text accumulated in a channel's separate stderr buffer. The first argument is the channel number and the second is the charset. The stderr buffer is cleared after the text is returned.

Background: This is only meaningful when StderrToStdout is false, which keeps error output in its own buffer instead of merging it into the normal receive buffer. Separating the two lets a program parse a command's real output cleanly while still capturing diagnostics — important because many Unix tools write warnings to stderr that would otherwise corrupt the parsed result. With merging enabled, this buffer stays empty and the text appears via GetReceivedText instead.

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Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Ssh;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  ssh: TSsh;
  sshPort: Integer;
  password: string;
  channelNum: Integer;
  stdoutText: string;
  stderrText: string;

begin
  success := False;

  //  Demonstrates the Ssh.GetReceivedStderrText method, which decodes and returns the text in a
  //  channel's separate stderr buffer.  The 1st argument is the channel number and the 2nd is the
  //  charset.  The stderr buffer is cleared after the text is returned.

  ssh := TSsh.Create;

  sshPort := 22;
  success := ssh.Connect('ssh.example.com',sshPort);
  if (success = False) then
    begin
      WriteLn(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 = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Keep stderr in its own buffer rather than merging it into the normal receive buffer.
  ssh.StderrToStdout := False;

  channelNum := ssh.OpenSessionChannel();
  if (channelNum < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Run a command that writes to both stdout and stderr.
  success := ssh.SendReqExec(channelNum,'ls /etc/hosts /no/such/path');
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
  //  it, this call waits forever if the server never sends channel close.
  ssh.ReadTimeoutMs := 15000;

  success := ssh.ChannelReceiveToClose(channelNum);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  stdoutText := ssh.GetReceivedText(channelNum,'utf-8');
  if (ssh.LastMethodSuccess = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;
  WriteLn('STDOUT: ' + stdoutText);

  stderrText := ssh.GetReceivedStderrText(channelNum,'utf-8');
  if (ssh.LastMethodSuccess = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;
  WriteLn('STDERR: ' + stderrText);

  ssh.Disconnect();


  ssh.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.