Laziness and the exclamation mark

History expansion was born in Bill Joy's csh, in the seventies, and bash and zsh carry it to this day: an exclamation mark that, at the start of a word, stops being punctuation and becomes a request — bring back that line, that word, that piece.

The article Your shell and the lazy exclamation mark, which served as this reliquary's collecting expedition, argues that this is the don't-repeat-yourself principle applied to the terminal: if the argument has been typed once, typing it again is a waste of keyboard.

The grammar, in one line

Every expression has up to three parts: an event (which line of history), a word (which piece of it) and modifiers (what to do with the piece), separated by colons. !ssh:1:h reads: from the last line that started with ssh, the first word, directory only.

Almost everything abbreviates — !!:$ becomes !$, !!:1 becomes !^ — and the abbreviations are where the collection touches everyday life: the article suggests taking four pieces home, !$, !:0, !$:h and !$:t.

Why almost nobody calls them

Because they run without showing. Ctrl+R and Alt+. won the habit precisely by keeping the line in sight before Enter — which is why they live here in the neighboring tools drawer, not as rivals but as kin. The :p modifier is the bridge: it prints without running.

And some prefer to retire the whole thing: the containment drawer keeps the switch that turns history expansion off entirely.

Why lots of little pages

For the same reason as the herbarium: every relic, every drawer, every ordering and this very text are separate HTML files, linked together, written by a generator a few hundred lines long. State becomes an address; the browser handles the rest.