In Drupal, a tool for controlling access to content creation, modification and site administration at the application level. Administrators assign permissions to roles, then assign roles to users. The first user of a Drupal site () automatically receives all permissions. In operating systems like UNIX, permissions are security settings restricting or allowing users to access information or perform certain functions at the operating system level. In the case of files on UNIX systems, there are three types of permissions: read, write and execute.