{
  "id": "linux-process-management",
  "title": "Find and Stop a Runaway Process",
  "category": "Linux Fundamentals",
  "isolation_type": "shared_namespace",
  "difficulty": "Easy",
  "type": "task",
  "weight": 4,
  "description": "## Find and Stop a Runaway Process\n\nA background process has been started for you and its PID recorded at `/srv/proc-lab/target.pid`. Every process in Kubernetes and Docker is, underneath, exactly this: a PID the kernel is tracking.\n\n**Your task:**\n\n1. Confirm the process is currently running (`kill -0 <pid>` succeeds silently if a process exists)\n2. Send it a termination signal: `kill <pid>` (using the PID recorded in the file, not a hardcoded number — it will be different every time)\n3. Confirm it is actually gone afterward",
  "hints": [
    {
      "title": "Reading the PID and checking it's alive",
      "body": "`kill -0` sends no real signal — it only checks whether the process exists, which is why it's the standard way to test \"is this PID still running\" without side effects.",
      "command": "cat /srv/proc-lab/target.pid\nkill -0 $(cat /srv/proc-lab/target.pid) && echo RUNNING"
    },
    {
      "title": "Terminating it",
      "body": "A plain `kill <pid>` sends SIGTERM, the polite \"please shut down\" signal — the correct first choice before ever reaching for `kill -9`.",
      "command": "kill $(cat /srv/proc-lab/target.pid)"
    }
  ],
  "setup_commands": [
    { "command": "mkdir -p /srv/proc-lab && (sleep 900 & echo $! > /srv/proc-lab/target.pid)" }
  ],
  "validation": {
    "commands": [
      { "description": "the target process has actually been terminated", "command": "kill -0 $(cat /srv/proc-lab/target.pid) 2>/dev/null && echo RUNNING || echo GONE", "expected_output": "GONE", "match": "exact" }
    ]
  },
  "default_namespace": "default",
  "teardown_commands": [
    { "command": "kill -9 $(cat /srv/proc-lab/target.pid) 2>/dev/null; rm -rf /srv/proc-lab" }
  ]
}