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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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const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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.

    const sftp = try chilkat.SFtp.init();
    defer sftp.deinit();

    // Connect, authenticate, and initialize the SFTP subsystem.
    const port = 22;
    sftp.connect("sftp.example.com", port) catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        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 password = "mySshPassword";

    sftp.authenticatePw("mySshLogin", password) catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

    sftp.initializeSftp() catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

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

    // Interpret the return value.
    if (result == -1) {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    }

    if (result == 0) {
        std.debug.print("The path does not exist.\n", .{});
    }

    if (result == 1) {
        std.debug.print("A regular file exists.\n", .{});
    }

    if (result == 2) {
        std.debug.print("A directory exists.\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();
}