Developing Simple POSIX Shell Scripts¶

Simple POSIX shell scripts cover ad-hoc tasks, short wrappers, and linear logic that does not need full CLI scaffolding.

Prioritise correctness, brevity, and portability. SHOULD NOT pad simple scripts with template boilerplate.

See common.md for baseline requirements (shebang, safety modes, tooling, POSIX compliance, logic, quoting).

Notes¶

Use positional arguments ("${1}", "${2}"); use :? for mandatory arg validation.

Minimal Example¶

#!/bin/sh

set -e
set -u

src="${1:?Usage: $0 <src> <dst>}"
dst="${2:?Usage: $0 <src> <dst>}"

if [ ! -f "${src}" ]; then
    printf 'Source file not found: %s\n' "${src}" >&2
    exit 1
fi

cp "${src}" "${dst}"
printf 'Copied %s -> %s\n' "${src}" "${dst}"

Upgrade to Complex¶

When the script meets any Complex criterion from the skill's classification (roughly 50 lines, 3+ flags, structured logging, -h/help output, cleanup, or shared use), refactor with developing-complex-posix-shell-scripts.md and reference-code-blocks.md.