One-time Scheduling with at

# Introduction

While `cron` is ideal for recurring jobs (daily, hourly), sometimes you need to schedule a task to run only once at a specific time in the future. For example, you might want to restart a service at 2:00 AM tonight, or take a database snapshot in 30 minutes.

For these one-off tasks, Linux provides the `at` utility.

The `at` command reads commands from standard input or a file and executes them at a later time. This is useful when the task is delayed but not recurring, which is different from cron's repeating schedule model.

So the main conceptual difference is simple: `cron` describes repeating schedules, while `at` queues a one-time future job. Both are automation tools, but they solve different timing problems.

In this lab, you will:

1. **Install Prerequisites**: Ensure the `at` utility and daemon are running.
2. **Schedule a Job**: Use `at` to queue a command for future execution.
3. **Inspect the Queue**: Use `atq` to list pending jobs.
4. **Manage Jobs**: Use `atrm` to remove a job from the queue.