Java

Check if a Remote File or Directory Exists

Demonstrates the Chilkat SFtp.FileExists method, which checks a remote path and returns an integer describing what is there. The first argument is the remote path and the second (followLinks) selects whether a symbolic link is followed to its target. The return value is -1 on error, 0 if nothing exists, 1 for a file, 2 for a directory, 3 for a symbolic link, and higher values for special entry types.

Background: This returns more than a yes/no because "does it exist" usually comes with "and is it the kind of thing I expect" — a job that means to write a file should notice if a directory already occupies the path. The followLinks flag decides whether a symbolic link is reported as a link (3, only when not following) or transparently resolved to its target's type. Always handle the -1 case: it means the check itself failed, which is different from the path not existing.

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

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the SFtp.FileExists method, which checks a remote path and returns an integer
        // describing what is there.  The 1st argument is the remote path and the 2nd (followLinks)
        // selects whether a symbolic link is followed to its target.

        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();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // When followLinks is true, a symbolic link is followed and the target's type is returned.
        boolean followLinks = true;
        int result = sftp.fileExists("subdir/report.pdf", followLinks);

        // Interpret the return value.
        if (result == -1) {
            System.out.println(sftp.getLastErrorText());
            return;
        }

        if (result == 0) {
            System.out.println("The path does not exist.");
        }

        if (result == 1) {
            System.out.println("A regular file exists.");
        }

        if (result == 2) {
            System.out.println("A directory exists.");
        }

        // Other possible values: 3 = symbolic link (only when followLinks is false), 4 = special
        // entry, 5 = unknown, 6 = socket, 7 = character device, 8 = block device, 9 = FIFO.

        sftp.disconnect();
    }
}