---
title: "Custom Boot Scripts"
slug: "fmadio-os-custom-boot-scripts"
updated: 2024-11-21T14:33:21Z
published: 2024-11-21T14:33:21Z
canonical: "docs.fmad.io/fmadio-os-custom-boot-scripts"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fmad.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Boot Scripts

As FMADIO OS is effectively a ROM based distribution, where by default everything runs off RAM disk. The ability to customize the boot startup process can be helpful.

There is a lua boot script located in

`/opt/fmadio/etc/boot.lua`

This script gets once on system startup during the booting process, and can be used for multiple things such as

- custom TLS certificates
- persistent SSH tunnels
- customizing file locations

And many other things, one approach is to use this file to execute typical bash scripts that sysadmins are more familiar with (than the Lua language).

---

## Custom Directory

First example is creating a specific directory path on the RAM based file system, in this case it creates the directory

`/opt/my_application/bin/`

### Step 1) Create boot.lua

The example `boot.lua` file is shown below

```plaintext
os.execute("mkdir -p /opt/my_application/bin/")
os.execute("touch /opt/my_application/bin/example")
```

### Step 2) Validate the Syntax

After editing the file recommended to check the syntax of the `boot.lua` using

`fmadiolua /opt/fmadio/etc/boot/lua`

Example output looks like the following

```plaintext
fmadio@fmadio200v4-636:~$ fmadiolua /opt/fmadio/etc/boot.lua
fmad fmadlua Nov 21 2024 (fmadiolua /opt/fmadio/etc/boot.lua )
Cycles/Sec 2750017930.0000 Std:       0 cycle std(  0.00000000) Target:2.75 Ghz
failed to open self? [fmadiolua]
done 0.001534Sec 0.000026Min
fmadio@fmadio200v4-636:~$
```

Any syntax errors will be printed out

### Step 3) Reboot the system

Reboot the system using

`sudo reboot`

### Step 4) Check path exists

After the system has rebooted check the directory and path create in step 1) exists

```plaintext
fmadio@fmadio100v2-228U:~$ ls -al /opt/my_application/bin
total 0
drwxr-xr-x    2 root     root            60 Nov 21 22:29 ./
drwxr-xr-x    3 root     root            60 Nov 21 22:29 ../
-rw-r--r--    1 root     root             0 Nov 21 22:29 example
fmadio@fmadio100v2-228U:~$
```

### Step 5) Finish

Completed