shell

name	shell
description	Efficient shell command handling. You MUST load this skill when handling shell commands with performance monitoring or timeouts.
license	MIT

Shell Handling Skill

Execute shell commands with performance monitoring and timeout protection.

When to Use

• Commands that might hang indefinitely
• Long-running commands (builds, tests, deployments)
• Performance optimization and debugging

When Not to Use

• Quick, reliable commands that execute in milliseconds
• Interactive terminal sessions requiring human input
• Operations better handled by specialized built-in agents or native APIs

Common Pitfalls

• Ignoring Exit Codes: Piping with time or timeout can mask the exit code of the underlying command. Use set -o pipefail or check $? carefully.
• Overly Aggressive Timeouts: Setting a timeout too close to the expected duration can cause false failures on slower environments (like CI/CD). Add a healthy buffer.
• Runaway Child Processes: timeout might not kill child processes spawned by the target command unless used with --kill-after or running in a new process group.

Core Patterns

Measure Execution Time

Prefix commands with time for duration visibility:

time command
time npm run build

Limit Execution Time

Use timeout to prevent indefinite hangs:

timeout 30s command
timeout 60s npm test || echo "Failed or timed out"

Combined Usage

time timeout 300s build_script.sh

Key Points

• Combine with || for error handling fallbacks
• Set timeout based on expected runtime plus buffer
• Use time for all long operations to track performance
• timeout --kill-after=5s 30s for forceful termination if needed
• If command results are unexpected, briefly explain what happened and why.

Related Skills

• robust-commands: You MUST load this skill when executing commands requiring resilient error recovery or fallbacks.