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System Startup

MOS provides dedicated hooks that are executed during system startup. These hooks allow controlled customization of the boot process.

Pre-Start Script (pre-start.sh)​

The Pre-Start Script is executed very early during system startup.

It runs before storage pools are mounted and before any services are started. This makes it suitable for preparing the system environment before MOS initializes storage, containers, and virtual machines.

📍 Script Location​

/boot/optional/scripts/pre-start.sh

If this file exists, MOS will automatically execute it during every system boot.

⏱️ Execution Order​

The Pre-Start Script is executed in the following phase:

  1. Early system initialization
  2. Before storage pools are mounted
  3. Before Docker, LXC, VM, and other services are started

At this stage, only the base system is available.

🔧 Typical Use Cases​

  • Early hardware initialization
  • Loading kernel modules
  • Network preparation required before pool mounting
  • Low-level system configuration
  • Preparing devices required before services start

🧭 Recommended Usage​

While MOS provides startup scripts for early system customization, it is strongly recommended to use Cron jobs whenever possible.

Cron jobs:

  • Run in a fully initialized system environment
  • Are easier to manage and debug
  • Reduce the risk of boot-time failures
  • Are suitable for most automation tasks

Startup scripts should only be used when actions must run before pools are mounted or services are started.

📌 Script Execution Notes​

  • Startup scripts do not need to be executable
  • No chmod +x is required
  • Script execution is handled internally by MOS

As long as the script file exists at the correct path, MOS will execute it automatically.

⚠️ Important Notes​

  • Storage pools are not available at this stage
  • Services are not running yet
  • Logging and output are limited
  • Errors in this script can affect system startup

Use this script carefully and keep it as minimal as possible.

✅ Summary​

  • Runs very early during system startup
  • Executed before pools and services
  • Intended for early system preparation
  • Cron jobs are preferred whenever possible
  • Part of the official MOS startup process

Parts of this documentation were created with the assistance of AI tools. All AI-generated content has undergone review, but it may still contain inaccuracies, omissions, or outdated information.