Pascal (Lazarus/Delphi)

Check if a Remote File or Directory Exists

Demonstrates the Chilkat SFtp.FileExists method, which checks a remote path and returns an integer describing what is there. The first argument is the remote path and the second (followLinks) selects whether a symbolic link is followed to its target. The return value is -1 on error, 0 if nothing exists, 1 for a file, 2 for a directory, 3 for a symbolic link, and higher values for special entry types.

Background: This returns more than a yes/no because "does it exist" usually comes with "and is it the kind of thing I expect" — a job that means to write a file should notice if a directory already occupies the path. The followLinks flag decides whether a symbolic link is reported as a link (3, only when not following) or transparently resolved to its target's type. Always handle the -1 case: it means the check itself failed, which is different from the path not existing.

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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.SFtp;

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

procedure RunDemo;
var
  success: Boolean;
  sftp: TSFtp;
  port: Integer;
  password: string;
  followLinks: Boolean;
  result: Integer;

begin
  success := False;

  //  Demonstrates the SFtp.FileExists method, which checks a remote path and returns an integer
  //  describing what is there.  The 1st argument is the remote path and the 2nd (followLinks)
  //  selects whether a symbolic link is followed to its target.

  sftp := TSFtp.Create;

  //  Connect, authenticate, and initialize the SFTP subsystem.
  port := 22;
  success := sftp.Connect('sftp.example.com',port);
  if (success = False) then
    begin
      WriteLn(sftp.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 := sftp.AuthenticatePw('mySshLogin',password);
  if (success = False) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  success := sftp.InitializeSftp();
  if (success = False) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  //  When followLinks is True, a symbolic link is followed and the target's type is returned.
  followLinks := True;
  result := sftp.FileExists('subdir/report.pdf',followLinks);

  //  Interpret the return value.
  if (result = -1) then
    begin
      WriteLn(sftp.LastErrorText);
      Exit;
    end;

  if (result = 0) then
    begin
      WriteLn('The path does not exist.');
    end;

  if (result = 1) then
    begin
      WriteLn('A regular file exists.');
    end;

  if (result = 2) then
    begin
      WriteLn('A directory exists.');
    end;

  //  Other possible values: 3 = symbolic link (only when followLinks is False), 4 = special
  //  entry, 5 = unknown, 6 = socket, 7 = character device, 8 = block device, 9 = FIFO.

  sftp.Disconnect();


  sftp.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.