redirect.js

    function tempRedirect(req, res) {
        var filename = req.params[0];
        var params = {
            Bucket: S3_BUCKET,
            ResponseContentDisposition: 'inline; filename=' + filename.replace(/,/, '_'),
            Key: checkTrailingSlash(getFileKeyDir(req)) + filename
        };
        var s3 = new aws.S3(s3Options);
        s3.getSignedUrl('getObject', params, function(err, url) {
            res.redirect(url);
        });
    };