Background Tasks

Background Tasks Skill

Manage long-running shell processes without blocking the terminal. All scripts output JSON for easy parsing.

Quick Start

cd .claude/skills/background-tasks/scripts

# Start a task in background
./start.sh "npm run dev" --name "dev-server"

# List running tasks
./list.sh

# Get task output
./output.sh --id <task-id>
# or by name
./output.sh --name "dev-server"

# Kill a task
./kill.sh --id <task-id>
# or by name
./kill.sh --name "dev-server"

Available Scripts

All scripts are in .claude/skills/background-tasks/scripts/

Core Scripts

Script Usage

start.sh - Start Background Task

# Basic usage
./start.sh "npm run dev"

# With name for easy reference
./start.sh "npm run dev" --name "dev-server"

# With working directory
./start.sh "cargo build" --name "rust-build" --cwd /path/to/project

# With environment variables
./start.sh "node server.js" --name "api" --env "PORT=3000,NODE_ENV=production"

Output:

{
  "success": true,
  "id": "bg_1234567890",
  "name": "dev-server",
  "pid": 12345,
  "command": "npm run dev",
  "cwd": "/path/to/project",
  "started_at": "2025-01-15T10:30:00Z",
  "log_file": "/tmp/bg_tasks/bg_1234567890.log"
}

list.sh - List Active Tasks

# List running tasks
./list.sh

# Include completed/failed tasks
./list.sh --all

# Filter by status
./list.sh --status running
./list.sh --status completed
./list.sh --status failed

Output:

{
  "success": true,
  "tasks": [
    {
      "id": "bg_1234567890",
      "name": "dev-server",
      "pid": 12345,
      "status": "running",
      "command": "npm run dev",
      "started_at": "2025-01-15T10:30:00Z",
      "duration": "5m 30s"
    }
  ],
  "count": 1
}

output.sh - Get Task Output

# Get all output by ID
./output.sh --id bg_1234567890

# Get by name
./output.sh --name "dev-server"

# Last N lines only
./output.sh --name "dev-server" --tail 50

# Filter output with grep pattern
./output.sh --name "dev-server" --filter "error|warning"

# Stream output (like tail -f)
./output.sh --name "dev-server" --follow

Output:

{
  "success": true,
  "id": "bg_1234567890",
  "name": "dev-server",
  "status": "running",
  "output": "Server started on port 3000\nListening...\n",
  "lines": 2
}

kill.sh - Terminate Task

# Kill by ID
./kill.sh --id bg_1234567890

# Kill by name
./kill.sh --name "dev-server"

# Send specific signal (default: SIGTERM)
./kill.sh --name "dev-server" --signal SIGKILL

# Kill all tasks
./kill.sh --all

Output:

{
  "success": true,
  "id": "bg_1234567890",
  "name": "dev-server",
  "pid": 12345,
  "signal": "SIGTERM",
  "killed": true
}

cleanup.sh - Remove Completed Task Records

# Clean up completed tasks older than 1 hour (default)
./cleanup.sh

# Clean up all completed tasks
./cleanup.sh --all

# Clean up tasks older than N minutes
./cleanup.sh --older-than 30

Common Workflows

Development Server

# Start dev server in background
./start.sh "npm run dev" --name "frontend" --cwd ./apps/web

# Check if running
./list.sh | jq '.tasks[] | select(.name=="frontend")'

# View logs when debugging
./output.sh --name "frontend" --tail 100

# Restart server
./kill.sh --name "frontend"
./start.sh "npm run dev" --name "frontend" --cwd ./apps/web

Parallel Build Tasks

# Start multiple builds
./start.sh "npm run build:client" --name "build-client"
./start.sh "npm run build:server" --name "build-server"
./start.sh "npm run build:shared" --name "build-shared"

# Monitor all
./list.sh

# Wait for completion and check results
./output.sh --name "build-client" --filter "error"
./output.sh --name "build-server" --filter "error"

Watch Mode

# Start test watcher
./start.sh "npm run test:watch" --name "tests"

# Start type checker in watch mode
./start.sh "npx tsc --watch" --name "tsc"

# Check for errors periodically
./output.sh --name "tsc" --filter "error"

Long-Running Processes

# Start database
./start.sh "docker compose up db" --name "postgres"

# Start API server
./start.sh "npm run api:dev" --name "api" --env "DATABASE_URL=postgres://..."

# Cleanup when done
./kill.sh --all
./cleanup.sh --all

Task States

Storage

Task metadata and logs are stored in /tmp/bg_tasks/:

• tasks.json - Task registry with metadata
• <task-id>.log - Combined stdout/stderr for each task

Error Handling

All scripts return JSON with success: false on error:

{
  "success": false,
  "error": "Task not found: dev-server"
}

Common errors:

• Task not found (invalid ID or name)
• Task already completed
• Permission denied
• Command not found

Troubleshooting

Task shows "running" but process is dead

# Force refresh task status
./list.sh --refresh

Can't kill zombie process

# Use SIGKILL
./kill.sh --name "stuck-process" --signal SIGKILL

Log files growing too large

# Clean up old logs
./cleanup.sh --older-than 60

Find orphaned processes

# List all processes with their PIDs
./list.sh | jq '.tasks[] | {name, pid}'
# Then verify with: ps -p <pid>

Integration Notes

• All output is JSON to stdout for easy parsing with jq
• Exit codes: 0 = success, 1 = error
• Errors output to stderr as JSON
• Task names must be unique; starting a task with existing name fails
• Use --name for human-readable references vs auto-generated IDs