IFS AND FIELD SPLITTING

Two kinds of delimiter: white ones merge into one, non-white ones each cut on their own — and the same value gives one field or four

Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.

Three sizes in one archive — from a sheet on the fridge to a poster on the wall.

Formats: A4 · A3 · A2
What you get: Print-ready PDFs, one per size, with every letterform converted to outlines — nothing to install, nothing to shift.
Subject: code · everyone · memo · study

Read from top to bottom: how many fields one value gives under different IFS, by what rule each kind of delimiter cuts, and where IFS decides anything. Every field was printed by /bin/sh.

A DELIMITER AT THE FRONT GIVES AN EMPTY FIELD, THE SAME ONE AT THE END DOES NOT

A colon at the front gives an empty field, a colon at the end does not: “the candidate shall become an output field if and only if it is not empty”. So “:a:” with IFS set to a colon gives two fields, not three, and the first of them is empty.

Because of that a line like “a::b:” gives three fields, not four, and the last empty field disappears without a word. That is exactly where counting the columns of a colon-separated file goes wrong.

On the sheet

Read from top to bottom: how many fields one value gives under different IFS, by what rule each kind of delimiter cuts, and where IFS decides anything. Every field was printed by /bin/sh.
Colour carries meaning, but meaning never rests on colour alone — the sheet reads in black and white.
Nothing about how it was made: the sheet carries only what the reader needs.

Printing

Three sizes in the archive: A4 — 210×297 mm, A3 — 297×420 mm, A2 — 420×594 mm.
All text is converted to outlines. No fonts to install, and nothing shifts on another machine.
White background and sparing fills — it prints on a home printer without draining the cartridge.
Margins of at least 10 mm: a home printer cannot print to the edge.
No stroke thinner than 0.3 mm, so nothing disappears in print.

Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 11 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.

IFS AND FIELD SPLITTING

A DELIMITER AT THE FRONT GIVES AN EMPTY FIELD, THE SAME ONE AT THE END DOES NOT

On the sheet

Printing

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