Android™

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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// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  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.

    CkSFtp sftp = new CkSFtp();

    //  Connect, authenticate, and initialize the SFTP subsystem.
    int port = 22;
    success = sftp.Connect("sftp.example.com",port);
    if (success == false) {
        Log.i(TAG, sftp.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.
    String password = "mySshPassword";

    success = sftp.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    success = sftp.InitializeSftp();
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    //  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 == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    Log.i(TAG, "Hard link created.");

    sftp.Disconnect();

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}