Pickins are pretty slim for what OP wants but, if you are willing to use an android phone the following app will let you run a lot of handy commands I associate with gnu linux based distributions. (convert, ls -ltr, vi, and so on). Root is not needed. One caveat is that it doesn't work on android versions lollipop and Marshmellow. But it works fine on, say, kitkat, and below which is found on many devices. You might consider getting a Note 3 which has pretty good performance and also has a stylus and a big enough screen so that when you use the touch keyboard (use hackers if you want tab and Ctrl C,tab at fingertips) it is roughly equivalent area wise to the N900 with keyboard slid out. It's all open source so feel free to improve!

https://play.google.com/store/apps/d...zshaolin&hl=en

here are some screen shots