Fluency on the command line is a skill often neglected or considered arcane, but it improves your flexibility and productivity as an engineer in both obvious and subtle ways. This is a selection of notes and tips on using the command-line that we've found useful when working on Linux. Some tips are elementary, and some are fairly specific, sophisticated, or obscure. This page is not long, but if you can use and recall all the items here, you know a lot.

[2000-08-09]

The Joel Test

1.    Do you use source control?
2.    Can you make a build in one step?
3.    Do you make daily builds?
4.    Do you have a bug database?
5.    Do you fix bugs before writing new code?
6.    Do you have an up-to-date schedule?
7.    Do you have a spec?
8.    Do programmers have quiet working conditions?
9.    Do you use the best tools money can buy?
10.    Do you have testers?
11.    Do new candidates write code during their interview?
12.    Do you do hallway usability testing?

TeXcount is a Perl script for counting words in LaTeX documents. It parses valid LaTeX documents counting words, headers, formulae (mathematics) and floats/begin-end groups.

Collection of 39 single-player open-source logic puzzle games, free, no ads, playable offline.

All generated on demand with adjustable size/difficulty, so you'll never run out of puzzles.

Contains the following 39 games:
Black Box, Bridges, Cube, Dominosa, Fifteen, Filling, Flip, Flood, Galaxies, Guess, Inertia, Keen, Light Up, Loopy, Magnets, Map, Mines (Minesweeper), Net, Netslide, Palisade, Pattern, Pearl, Pegs (Solitaire), Range, Rectangles, Same Game, Signpost, Singles, Sixteen, Slant, Solo (Sudoku), Tents, Towers, Tracks, Twiddle, Undead, Unequal, Unruly, Untangle

On February 6th, 2018 SpaceX launched a Tesla Roadster on a Mars crossing orbit. We perform N-body simulations to determine the fate of the object over the next several million years, under the relevant perturbations acting on the orbit. The orbital evolution is initially dominated by close encounters with the Earth. The first close encounter with the Earth will occur in 2091. The repeated encounters lead to a random walk that eventually causes close encounters with other terrestrial planets and the Sun. Long-term integrations become highly sensitive to the initial conditions after several such close encounters. By running a large ensemble of simulations with slightly perturbed initial conditions, we estimate the probability of a collision with Earth and Venus over the next one million years to be 6% and 2.5%, respectively. We estimate the dynamical lifetime of the Tesla to be a few tens of millions of years.

Verz handy online version of BabelMap.

An interactive guide to alternative voting systems.