MultiOS-USB 0.10.1

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MultiOS-USB is a GRUB 2-powered multi-boot USB creator for Windows and Linux that places a clean boot menu on any drive and launches operating systems directly from ISO files - no reformatting, no proprietary bootloader, and no conversion step between adding a new image and booting it.

MultiOS-USB installs once to a USB drive, then stays out of the way entirely. Copy ISO files to the /ISOs directory, reboot, and choose which system to launch from a GRUB menu.

There is no application to keep running, no background service, and no daemon - the tool modifies the drive during setup and then operates passively from that point on.

The intended audience is broad: developers testing distributions across hardware, system administrators building recovery and diagnostic toolkits, IT technicians who maintain multi-boot drives for deployment, and power users who want a drive that behaves exactly like a standard GRUB installation and can be debugged with standard tools.

Installation: Windows and Linux

On Windows, installation uses the prebuilt MultiOS-USB_windows_image_v0.10.1.zip image.

Extract the archive, then write the image to your USB drive using a flashing tool. balenaEtcher is the simplest cross-platform option and verifies the write automatically.

Rufus is a fast Windows-native alternative if you prefer a single-file portable tool. Once written, the drive is ready - copy your ISO files to /ISOs and boot.

On Linux, run the shell script directly against your target device.

The script partitions the drive, installs GRUB 2, and creates the directory structure. It requires mkfs.fat to be available for EFI partition setup - version 0.10.1 adds an explicit check for this dependency before proceeding, which prevents silent failures on minimal systems.

SparkyLinux users can install from the package repository. NixOS users can run MultiOS-USB as a Nix flake with a single nix run command, with no permanent installation required.

How MultiOS-USB Fits into a Larger Workflow

The typical workflow looks like this:

Step 1 - Prepare your ISOs. Download distribution images for the systems you want to test or deploy. If you need to inspect or repack an ISO before adding it, PowerISO handles editing and conversion across all major image formats.

Step 2 - Install MultiOS-USB. Run the shell script against your target USB device from a Linux terminal. The script partitions the drive, installs GRUB 2, and creates the directory structure. SparkyLinux users can install from the package repository directly. NixOS users can run it as a Nix flake without permanent installation.

Step 3 - Copy your ISOs. Drop ISO files into /ISOs on the drive. MultiOS-USB now detects ISOs across all partitions on the drive, so you can organize images across multiple partitions if needed. For distributions without native GRUB loopback support, add custom configuration files to /config_priv - these survive tool updates. Version 0.10.1 ships configuration files for Bazzite, Debian netinst, and updated Debian configs out of the box.

Step 4 - Boot and select. Plug the drive into any BIOS or UEFI machine and boot from USB. The GRUB menu lists detected ISOs automatically. On first boot with Secure Boot enabled, enroll the MultiOS-USB certificate through the firmware interface once, and all subsequent boots proceed without disabling security features.

Step 5 - Extend with EFI tools. Version 0.10.1 adds support for detecting and chainloading EFI images stored in /MultiOS-USB/tools/. This means you can include UEFI utilities, firmware diagnostic tools, and EFI shell binaries alongside your ISOs and launch them from the same GRUB menu.

Once you have confirmed which distribution to install and are ready to commit to a dedicated drive, balenaEtcher handles single-image flashing with built-in verification across Linux, macOS, and Windows.

For concurrent duplication - creating multiple identical bootable drives from one image - ImageUSB writes to several USB drives simultaneously.

For network deployment to multiple machines without any physical drive at all, iVentoy extends the copy-and-boot model to PXE network booting.

Supported Distributions and File Systems

MultiOS-USB supports exFAT-formatted drives, removing the FAT32 4 GB file size ceiling. This matters when working with large Windows ISOs or current Linux distributions that exceed that limit. The same exfat boot capability has been extended to Debian 13 live images and SparkyLinux 8.0 in this release.

The tested distribution list is extensive. Ubuntu, Fedora (now including Fedora 42), Debian (including live and netinst variants and the upcoming Debian 13), openSUSE Leap (now including 16.0), Arch Linux, Kali Linux, Linux Mint, Manjaro, Pop!_OS, and Bazzite all work out of the box with verified configurations. Arch Linux installation instructions have been added to the project README in this release.

The new Nix flakes support means NixOS users can run MultiOS-USB with a single nix run command without adding it to their system configuration - useful for ephemeral environments or machines where you want no permanent footprint.

Comparison with Ventoy and YUMI

MultiOS-USB, Ventoy, and YUMI exFAT all follow the same core principle - copy ISOs, boot from a menu - but differ meaningfully in scope and approach.

Ventoy uses a custom bootloader that runs on Windows, Linux, and macOS and supports over 1,000 tested ISO files. YUMI exFAT uses the Ventoy bootloader internally and adds a Windows GUI wizard. Both tools are the better choice when you are setting up a drive from a Windows machine or need broad ISO compatibility with minimal configuration.

MultiOS-USB uses native GRUB 2 loopback exclusively, giving Linux administrators precise control over boot entries and configuration files while keeping the bootloader entirely standard. The absence of a proprietary component is the point for users who want a drive that behaves exactly like a regular GRUB installation and can be debugged with standard tools.

For guides on working with bootable media across these tools, see How to Add Multiple ISOs to One USB with YUMI exFAT, How to Copy Multiple ISOs to One USB Drive and Boot Any OS with Ventoy, and How to Create a Bootable Ubuntu USB Drive with Rufus.

If your goal after testing is to set up a permanent dual-boot environment, the How to Dual Boot Windows and Linux on the Same SSD guide covers the full process.

For portable Windows installations that run directly from external storage rather than installing to it, WinToUSB handles that workflow separately.

What's New in Version 0.10.1:

Expanded distribution support: Debian 13 live and SparkyLinux 8.0 now boot from exFAT-formatted drives. Fedora 42 and openSUSE Leap 16.0 have been added to the tested systems list. A new Bazzite configuration file enables ISO boot for that gaming-focused distribution. Debian netinst now has a dedicated configuration file.
New platform support: Nix flakes support has been added, allowing NixOS users to run MultiOS-USB without permanent installation. Arch Linux installation instructions have been added to the project README.
Core improvements: MultiOS-USB now detects ISOs across all partitions on the drive, not only the primary one. EFI image detection and chainloading from /MultiOS-USB/tools/ is now supported, enabling UEFI utilities and firmware tools to appear alongside operating system entries in the boot menu. An example configuration for running ISO files from a third partition has been added to the documentation.
Bug fixes: A shellcheck issue in multios-usb.sh has been resolved.