Java

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.

Chilkat Java Downloads

Download Chilkat for Java

Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.SFtp;

public class ChilkatExample {

    public static void main(String[] args) {
        // 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 sftp = new SFtp();

        // Connect, authenticate, and initialize the SFTP subsystem.
        int port = 22;
        try {
            sftp.connect("sftp.example.com", port);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            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";

        try {
            sftp.authenticatePw("mySshLogin", password);

            sftp.initializeSftp();

            // Create a hard link.  This uses the OpenSSH hardlink@openssh.com extension and succeeds only
            // when the server supports it.
            sftp.hardLink("subdir/data.bin", "subdir/data_backup.bin");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Hard link created.");

        sftp.disconnect();
    }
}