_TwoFinger

> One thing I found annoying was that it insisted on two spaces after a period.

GNU Emacs' manual has a good explanation:

The sentence commands assume that you follow the American typist's convention of putting two spaces at the end of a sentence. It is useful to follow this convention, because it allows the Emacs sentence commands to distinguish between periods that end a sentence and periods that indicate abbreviations.

Here's an interesting article that links shell scripting and relational algebra - http://matt.might.net/articles/sql-in-the-shell/

More importantly, your links have the full content. The article linked in the title is missing some diagrams, and others are way too small. Thanks!