Delphi ActiveX

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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var
success: Integer;
sftp: TChilkatSFtp;
port: Integer;
password: WideString;
followLinks: Integer;
result: Integer;

begin
success := 0;

//  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 := TChilkatSFtp.Create(Self);

//  Connect, authenticate, and initialize the SFTP subsystem.
port := 22;
success := sftp.Connect('sftp.example.com',port);
if (success = 0) then
  begin
    Memo1.Lines.Add(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 = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

success := sftp.InitializeSftp();
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

//  When followLinks is 1, a symbolic link is followed and the target's type is returned.
followLinks := 1;
result := sftp.FileExists('subdir/report.pdf',followLinks);

//  Interpret the return value.
if (result = -1) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

if (result = 0) then
  begin
    Memo1.Lines.Add('The path does not exist.');
  end;

if (result = 1) then
  begin
    Memo1.Lines.Add('A regular file exists.');
  end;

if (result = 2) then
  begin
    Memo1.Lines.Add('A directory exists.');
  end;

//  Other possible values: 3 = symbolic link (only when followLinks is 0), 4 = special
//  entry, 5 = unknown, 6 = socket, 7 = character device, 8 = block device, 9 = FIFO.

sftp.Disconnect();