bash-scripting

# Bash Scripting Orchestrates intelligent skill selection and execution for bash scripting workflows. Applies the 5 Laws of Elegant Defense to guide data naturally through the orchestration pipeline, preventing errors before they occur. Selects optimal skills based on multi-factor scoring including text similarity, historical performance, and system availability. ## TL;DR Checklist - [ ] Parse all inputs at boundary before processing (Law 2) - [ ] Handle edge cases with early returns at function top (Law 1) - [ ] Fail immediately with descriptive errors on invalid states (Law 4) - [ ] Return new data structures, never mutate inputs (Law 3) - [ ] Implement minimum 2-level fallback chain for all skill executions - [ ] Log all skill selections with context for full audit trail - [ ] Validate skill metadata and dependencies before selection - [ ] Update confidence scores after each execution for learning ┌───────────────────────────────────────────────────────────────────────────────┐ │ Orchestration Flow │ └───────────────────────────────────────────────────────────────────────────────┘ User Request ↓ ┌─────────────────┐ │ Parse Request │ │ & Extract │ │ Features │ └────────┬────────┘ ↓ ┌─────────────────────────────────────────────────────────────────────┐ │ Evaluate Available Skills │ │ │ │ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │ │ │ Skill A │ │ Skill B │ │ Skill C │ │ │ │ - Match Score│ │ - Match Score│ │ - Match Score│ │ │ │ - Confidence │ │ - Confidence │ │ - Confidence │ │ │ │ - History │ │ - History │ │ - History │ │ │ └──────┬───────┘ └──────┬───────┘ └──────┬───────┘ │ │ │ │ │ │ │ └─────────────────┴─────────────────┘ │ │ ↓ │ │ Select Best Skill │ └─────────────────────────────────────────────────────────────────────┘ ↓ ┌─────────────────┐ │ Execute Skill │ └────────┬────────┘ ↓ ┌─────────────────┐ │ Handle Result │ └────────┬────────┘ ↓ ┌─────────────────────────────────────────────────────────────────────┐ │ Error Handling & Fallback │ │ │ │ Success? ────────► Return Result │ │ │ │ Fail? ────────┐ │ │ ↓ │ │ ┌──────────────────────────────────────────────────────────┐ │ │ │ Fallback Chain │ │ │ │ │ │ │ │ 1. Retry with adjusted parameters │ │ │ │ 2. Try Alternative Skill (if available) │ │ │ │ 3. Defer to Human Operator (if critical) │ │ │ │ 4. Log & Return Error │ │ │ └──────────────────────────────────────────────────────────┘ │ └─────────────────────────────────────────────────────────────────────┘ ## When to Use Use this skill when: - Orchestrating multi-step workflows that require skill delegation - Implementing adaptive skill routing based on confidence scores - Building fallback mechanisms for failed skill executions - Creating intelligent task decomposition and parallel execution - Designing skill dependency graphs with automatic resolution - Implementing skill selection with historical performance weighting - Building agent systems that need to self-organize around tasks ## When NOT to Use Avoid this skill for: - Direct task execution without orchestration needs - use individual skills instead - High-frequency trading scenarios where latency must be minimized - the selection overhead may be prohibitive - Simple linear workflows without branching or fallback requirements - Cases where skill metadata is unavailable or unreliable ## Core Workflow 1. **Parse and Analyze Request** - Extract intent, entities, and constraints from user input. **Checkpoint:** All required parameters must be present and in valid format before proceeding. 2. **Score Available Skills** - Calculate match scores using multi-factor algorithm: - Text similarity between request and skill triggers - Historical success rate for similar tasks - Skill availability and health status - Required dependencies and their availability **Checkpoint:** Skip to fallback if no skill scores above threshold. 3. **Select Optimal Skill** - Choose skill with highest score that meets minimum confidence. **Checkpoint:** Verify skill has not been disabled or deprecated. 4. **Execute with Fallback** - Run skill execution wrapped in retry and fallback logic. **Checkpoint:** Log all execution attempts for audit trail. 5. **Return or Fallback** - Either return successful result or apply fallback chain: - Retry with adjusted parameters - Try alternative skill from `related-skills` - Defer to human operator for critical tasks **Checkpoint:** Record outcome with timing and confidence metadata. ## Implementation Patterns ### Pattern 1: Skill Selection Logic ```bash #!/usr/bin/env bash # Pattern 1: Bash Scripting with Early Exit & Input Validation # Implements Law 1 (Early Exit) and Law 2 (Make Illegal States Unrepresentable) set -euo pipefail SCRIPT_NAME="$(basename "$0")" LOG_FILE="/var/log/${SCRIPT_NAME}.log" # Guard clause: Validate required arguments immediately (Law 1) if [[ $# -lt 2 ]]; then echo "Usage: $SCRIPT_NAME <target_dir> <backup_prefix>" >&2 exit 1 fi TARGET_DIR="$1" BACKUP_PREFIX="$2" # Validate state: Ensure target exists and is a directory (Law 2) if [[ ! -d "$TARGET_DIR" ]]; then echo "ERROR: Target directory '$TARGET_DIR' does not exist or is not a directory." >&2 exit 2 fi # Parse and sanitize inputs - create immutable state snapshot TIMESTAMP=$(date +%Y%m%d_%H%M%S) BACKUP_NAME="${BACKUP_PREFIX}_${TIMESTAMP}.tar.gz" BACKUP_PATH="${TARGET_DIR}/backups/${BACKUP_NAME}" # Create backup directory if missing (atomic state transition) mkdir -p "${TARGET_DIR}/backups" # Execute core logic with strict error handling echo "Starting backup of ${TARGET_DIR} to ${BACKUP_PATH}..." if tar -czf "$BACKUP_PATH" -C "$(dirname "$TARGET_DIR")" "$(basename "$TARGET_DIR")"; then echo "SUCCESS: Backup completed at $(date)" # Log success with metadata for audit trail echo "$(date -Iseconds) | SUCCESS | ${BACKUP_NAME}" >> "$LOG_FILE" else echo "ERROR: tar command failed with exit code $?" >&2 exit 3 fi ``` ### Pattern 2: Execution with Fallback ```bash #!/usr/bin/env bash # Pattern 2: Bash Execution with Fallback Chain & Retry Logic # Implements Law 4 (Fail Fast, Fail Loud) and adaptive fallback routing set -euo pipefail MAX_RETRIES=3 RETRY_DELAY=2 # Function: Execute primary command with retry logic execute_with_retry() { local cmd="$1" local attempt=0 while (( attempt < MAX_RETRIES )); do if eval "$cmd"; then return 0 fi attempt=$((attempt + 1)) if (( attempt < MAX_RETRIES )); then echo "WARNING: Attempt $attempt failed. Retrying in ${RETRY_DELAY}s..." >&2 sleep "$RETRY_DELAY" fi done return 1 } # Fallback chain implementation run_fallback_chain() { local primary_cmd="$1" local fallback_cmd="$2" local critical_task="$3" # Attempt primary execution if execute_with_retry "$primary_cmd"; then echo "Primary execution succeeded." return 0 fi echo "Primary execution exhausted retries. Initiating fallback chain..." >&2 # Level 1: Retry with adjusted parameters (e.g., reduced concurrency) local adjusted_cmd="${primary_cmd} --concurrency=1" if execute_with_retry "$adjusted_cmd"; then echo "Fallback Level 1 (adjusted parameters) succeeded." return 0 fi # Level 2: Try alternative command/skill if [[ -n "$fallback_cmd" ]]; then if execute_with_retry "$fallback_cmd"; then echo "Fallback Level 2 (alternative command) succeeded." return 0 fi fi # Level 3: Critical task failure - escalate to human operator if [[ "$critical_task" == "true" ]]; then echo "CRITICAL: All fallbacks exhausted. Escalating to human operator." >&2 # Trigger alert mechanism curl -s -X POST "https://hooks.example.com/alert" \ -H "Content-Type: application/json" \ -d "{\"task\":\"$primary_cmd\",\"status\":\"failed\",\"escalated\":true}" || true return 2 fi echo "ERROR: All fallbacks failed. Task aborted." >&2 return 1 } # Example usage # run_fallback_chain "rsync -a /data /backup" "cp -r /data /backup" "false" ``` ### MUST DO - Always validate skill metadata before selection (Early Exit) - Implement fallback chain with at least 2 levels (Fallback Skill + Human) - Log all skill selections with full context for auditability - Return new data structures instead of mutating inputs (Atomic Predictability) - Fail immediately with descriptive errors on invalid states - Update confidence scores after each execution for adaptive routing - Reference `code-philosophy` (5 Laws of Elegant Defense) in all logic ### MUST NOT DO - Select skills based on a single factor (e.g., only confidence score) - Disable fallback mechanisms "temporarily" - this creates fragile systems - Skip validation of skill dependencies before execution - Return partial results - either complete success or clear failure - Use magic numbers for confidence thresholds - make them configurable - Cache skill selections without considering context changes ## TL;DR Checklist - [ ] Parse all inputs at boundary before processing (Law 2) - [ ] Handle edge cases with early returns at function top (Law 1) - [ ] Fail immediately with descriptive errors on invalid states (Law 4) - [ ] Return new data structures, never mutate inputs (Law 3) - [ ] Implement minimum 2-level fallback chain for all skill executions - [ ] Log all skill selections with context for full audit trail - [ ] Validate skill metadata and dependencies before selection - [ ] Update confidence scores after each execution for learning ## TL;DR for Code Generation - Use guard clauses - return early on invalid input before doing work - Return simple types (dict, str, int, bool, list) - avoid complex nested objects - Cyclomatic complexity < 10 per function - split anything larger - Handle null/empty cases explicitly at function top (Early Exit) - Never mutate input parameters - return new dicts/objects - Fail fast with descriptive errors - don't try to "patch" bad data - Reference code-philosophy laws in comments for complex logic - Include timing and confidence metadata in all return values ## Output Template When applying this skill, produce: 1. **Selected Skills** - List of skill names with confidence scores 2. **Selection Rationale** - Why each skill was chosen (match score, history, availability) 3. **Execution Plan** - Order of execution with dependencies 4. **Fallback Strategy** - Which fallback skills will be tried and in what order 5. **Risk Assessment** - Any potential failure points and their impact 6. **Timing Estimates** - Expected latency including fallback scenarios --- ## Constraints ### MUST DO - Define clear input/output contracts for every step in the orchestration flow with explicit validation - Implement structured logging at each stage capturing context, inputs, outputs, timing, and errors - Build in fallback paths: if the primary strategy fails, degrade gracefully to a simpler approach - Validate all preconditions before starting — do not proceed if required resources or permissions are missing ### MUST NOT DO - Do not create deep nesting of orchestration steps (>5 levels) — flatten workflows where possible - Avoid silent failure modes: every step must either succeed, fail explicitly, or escalate to a higher handler - Never use shared mutable state between parallel workflow branches — communicate via immutable messages only - Do not hardcode execution order when the dependency graph naturally determines it; derive order from explicit dependencies ## Related Skills | Skill | Purpose | |