dracut

Dracut is a Linux initramfs infrastructure and generator. It provides a kernel-agnostic framework for building initramfs images, which are loaded by the bootloader during early boot to initialize hardware and mount the real root filesystem. Dracut aims to produce a minimal, functional initramfs that adapts to the system’s hardware and configuration.

The core design of dracut is modular. It uses a plug-in architecture in which functionality is contributed by modules located under /usr/lib/dracut/modules.d. During image creation, dracut discovers and assembles the necessary modules and their dependencies, enabling components such as drivers, filesystems, and basic tools to be included in the initramfs. This modular approach allows distributions to tailor the generated image without changing the underlying tool.

Dracut is used by many Linux distributions, including Fedora, Red Hat Enterprise Linux, CentOS, Debian, and Arch Linux. It can generate initramfs images for a specific kernel version and supports various options to customize the output, such as choosing which modules to include or exclude and selecting the desired compression for the resulting image. A typical usage is to invoke dracut to produce a new initramfs file for the running kernel.

In operation, the initramfs created by dracut contains the early userspace required to initialize hardware, detect and mount storage, and switch to the real root filesystem. The module system also enables advanced setups such as encrypted disks (dm-crypt/LUKS), LVM, RAID, and other storage configurations. Overall, dracut provides a flexible and extensible mechanism for building initramfs across diverse Linux environments.