lib/api.js
function(user, path, cwd, cb) {
    logger.info('link system: ' + path + ', ' + cwd);
    _sr.linkSystem(user, path, cwd, cb);
  }
function(user, path, cwd, cb) {
    logger.info('link system: ' + path + ', ' + cwd);
    _sr.linkSystem(user, path, cwd, cb);
  }
link a system from local fs