Dart

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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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // 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.

  final sftp = CkSFtp();

  // Connect, authenticate, and initialize the SFTP subsystem.
  final port = 22;
  try {
    sftp.connect('sftp.example.com', port);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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.
  final password = 'mySshPassword';

  try {
    sftp.authenticatePw('mySshLogin', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    sftp.initializeSftp();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Create a hard link.  This uses the OpenSSH hardlink@openssh.com extension and succeeds only
  // when the server supports it.
  try {
    sftp.hardLink('subdir/data.bin', 'subdir/data_backup.bin');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Hard link created.');

  sftp.disconnect();
}