Delphi ActiveX

Create a Hard Link on an SFTP Server

Demonstrates the Chilkat SFtp.HardLink method, which creates a hard link to an existing remote file. The first argument is the existing file and the second is the new link path. It uses the OpenSSH hardlink@openssh.com extension and succeeds only when the server supports it.

Background: A hard link is a second name for the same file data, not a pointer to a path: both names are equal, the data persists until the last name is removed, and there is no "original" to break. Unlike a symbolic link it cannot span filesystems and cannot target a directory. Because it depends on a non-standard OpenSSH extension, expect it to fail against servers that do not implement it.

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

begin
success := 0;

//  Demonstrates the SFtp.HardLink method, which creates a hard link to an existing remote file.
//  The 1st argument is the existing file and the 2nd is the new link path.

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;

//  Create a hard link.  This uses the OpenSSH hardlink@openssh.com extension and succeeds only
//  when the server supports it.
success := sftp.HardLink('subdir/data.bin','subdir/data_backup.bin');
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Hard link created.');

sftp.Disconnect();