EL: A Shell for the Ethos Operating System

In this thesis we present the design and implementation of El, a new shell and scripting language for the Ethos operating system. The main goal of a shell is to bring operating system functionality and user space tools composition to the command line, and to provide a Programming Language (PL) for user space scripting. El aims to export an interface to the underlying Operating System (OS) that is as minimal as possible, making use of—and preserving—Ethos universal properties and abstractions. El is also intended to play a major role in Ethos user space programming, and thus is designed to overcome the issues of the major shells in use today in terms of PL abstractions. The result is an inherently safer shell and scripting environment, where attack surfaces that are common for other shells are removed by design.