PrintableCharts
THE EXIT STATUS

1 / 2 · mockup · mid-century

THE EXIT STATUS

One byte from a command to the shell: what the standard assigns in it, what it leaves to the system — and why “128 + signal number” is nowhere in the standard

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.

Free

By downloading you agree to the Terms.

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 the strip as one byte at true scale: on the left what the command itself says, on the right what happened to it, and in the seam between them the values the standard has taken.

“128 + SIGNAL NUMBER” IS A CUSTOM, NOT A RULE

The standard requires just three things: the status of a signal-terminated command is greater than 128, distinct for distinct signals, and its exact value is unspecified — it is even allowed past 255. The formula “128 + signal number” is nowhere in it: that is a custom of systems.

So one and the same status means both “a signal ended the command” and “the command exited with that value itself”: an application has no way to tell them apart.

On the sheet

  • Read the strip as one byte at true scale: on the left what the command itself says, on the right what happened to it, and in the seam between them the values the standard has taken.
  • 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 12 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.

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