Swift

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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func chilkatTest() {
    var success: Bool = 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.

    let sftp = CkoSFtp()!

    //  Connect, authenticate, and initialize the SFTP subsystem.
    var port: Int = 22
    success = sftp.connect(hostname: "sftp.example.com", port: port)
    if success == false {
        print("\(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.
    var password: String? = "mySshPassword"

    success = sftp.authenticatePw(login: "mySshLogin", password: password)
    if success == false {
        print("\(sftp.lastErrorText!)")
        return
    }

    success = sftp.initializeSftp()
    if success == false {
        print("\(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(oldPath: "subdir/data.bin", newPath: "subdir/data_backup.bin")
    if success == false {
        print("\(sftp.lastErrorText!)")
        return
    }

    print("Hard link created.")

    sftp.disconnect()

}