SOTA Shell Scripting

Purpose: produce shell scripts that survive contact with reality — unusual filenames, missing commands, partial failures, hostile input, signals, and concurrent invocation — and audit existing scripts for the defect classes that cause most production shell incidents: unquoted expansions, silent error swallowing, injection, secret leakage, and temp-file races.

Bash-focused (bash 5.x current; macOS ships bash 3.2 and defaults to zsh — see portability rules). POSIX sh only when the target demands it (busybox/dash containers, init systems).

First decision: should this be shell at all?

Do NOT use shell when any of these hold. Recommend Python/Go (or the project's primary language) instead, and say so explicitly in BUILD and AUDIT output: