Introductory statistics at minimum. p-values, different significance tests, precision vs. accuracy, sampling and bias.
Speed and use of keyboard shortcuts to the point that a mouse is unnecessary for 70%+ of tasks
Understand filesystem, ability to navigate a unix shell. https://en.wikipedia.org/wiki/List_of_Unix_commands
- ls, cd, pwd, tail, tee, strings, rm, patch, nohup, more, mkdir, man, ls, ln, kill, grep, find, fg, echo, du, diff, df, dd, date, cut, cp, chown, chmod, chgrp, cd, cat, bg, alias, sudo, umount
- extra credit: sed/awk, emacs/vi, curl, which, mkfs, lsblk, blkid