sh

name	sh
description	Bash/shell scripting. NOT for Python utilities (use py) or persistent CLI tools (use cli).
when_to_use	editing .sh files or writing shell scripts

Bash Style

Requires the software skill's code.md for shared naming, style, and design rules. Below are shell-specific additions.

Structure

• ALWAYS set -Eeuo pipefail at top, NEVER rely on set -e alone for pipelines
• ALWAYS tmp=$(mktemp -d) + trap 'rm -rf -- "$tmp"' EXIT for transient files; NEVER hand-roll /tmp/script-$$
• ALWAYS iterate find output with while IFS= read -r -d '' < <(find ... -print0) or mapfile -t arr < <(cmd); NEVER for f in $(find ...) or for f in $(ls)
• do/then/else on own line, NEVER after ; or &&
• Functions for repeated logic, plain sequence otherwise

Variables

• "${VAR:-default}" for optional, "${VAR:?msg}" for required
• ALWAYS quote: "$VAR" not $VAR
• Uppercase for env/config, lowercase for locals

Conditionals

• [[ ]] not [ ] (bash scripts)
• Booleans: flag=false then if $flag; then (not string comparison)
• NEVER forget closing ] when then is on next line

Loops

• ALWAYS shopt -s globstar + **/*.ext over find for simple recursion
• NEVER pipe into while when loop body sets variables (subshell loses state)

Process

• trap 'cleanup' INT TERM for graceful shutdown
• wait after backgrounding

Fallback Patterns

SEED="/preferred/path"
[ -d "$SEED" ] || SEED="fallback/path"

Heredocs

• cat <<EOF for multi-line output
• <<'EOF' for no expansion

Anti-patterns

• NEVER inline ; then or ; do
• NEVER unquoted variables
• NEVER sudo in authored/committed scripts (ask user / parameterize privilege). The agent's own ad-hoc Bash-tool docker commands use sudo per WISDOM.