C++

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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#include <CkSFtp.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  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.

    CkSFtp sftp;

    //  Connect, authenticate, and initialize the SFTP subsystem.
    int port = 22;
    success = sftp.Connect("sftp.example.com",port);
    if (success == false) {
        std::cout << sftp.lastErrorText() << "\r\n";
        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.
    const char *password = "mySshPassword";

    success = sftp.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        std::cout << sftp.lastErrorText() << "\r\n";
        return;
    }

    success = sftp.InitializeSftp();
    if (success == false) {
        std::cout << sftp.lastErrorText() << "\r\n";
        return;
    }

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

    //  Interpret the return value.
    if (result == -1) {
        std::cout << sftp.lastErrorText() << "\r\n";
        return;
    }

    if (result == 0) {
        std::cout << "The path does not exist." << "\r\n";
    }

    if (result == 1) {
        std::cout << "A regular file exists." << "\r\n";
    }

    if (result == 2) {
        std::cout << "A directory exists." << "\r\n";
    }

    //  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();
    }