Symbolic mathematics on Linux

SageMathCloud entirely runs on Linux, provides a free Linux command shell in the cloud, and I think *everything* mentioned in this article is already pre-installed there -- so it seems pretty relevant! You can also very easily install a Docker image of SageMathCloud and run it on your own computer. I'm on 100% leave from my tenured academic position, since the department convinced me not to resign just yet. They have very recently been extremely supportive regarding intellectual property and other dicy issues. (Disclaimer: I'm the founder of SageMath.)