Developing Simple Bash Scripts

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

Prioritise correctness and brevity. Do not pad simple scripts with template boilerplate.

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

Notes

• errtrace is not required.
• Use positional arguments ("${1}", "${2}"); use :? for mandatory arg validation.
• Use Bash-specific features such as arrays, process substitution, and here-strings whenever they simplify the logic - see common.md.

Minimal Example

#!/usr/bin/env bash

set -o errexit -o nounset

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

if [[ ! -f "${src}" ]]; then
    echo "Source file not found: ${src}" >&2
    exit 1
fi

cp "${src}" "${dst}"
echo "Copied ${src} -> ${dst}"

Upgrade to Complex

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