mkfs.erofs

creates EROFS images from a directory tree

TLDR

Create an EROFS filesystem based on the root directory

$ mkfs.erofs [image.erofs] [root/]

Create an EROFS image with a specific UUID

$ mkfs.erofs -U [UUID] [image.erofs] [root/]

Create a compressed EROFS image

$ mkfs.erofs -zlz4hc [image.erofs] [root/]

Create an EROFS image where all files are owned by root

$ mkfs.erofs --all-root [image.erofs] [root/]

SYNOPSIS

mkfs.erofs [options] image source

mkfs.erofs creates EROFS (Enhanced Read-Only File System) images from a directory tree. EROFS is a lightweight read-only filesystem designed for performance-sensitive scenarios like Android system partitions, container images, and embedded systems.The filesystem supports transparent compression, enabling significant space savings while maintaining fast random read access. Unlike SquashFS, EROFS provides better random access performance due to its fixed-size block design.Output is a file containing the complete filesystem image, suitable for mounting via loopback or writing to a read-only partition.

PARAMETERS

-U _uuid_

Set a specific filesystem UUID

-z _algorithm_

Enable compression (lz4, lz4hc, lzma, deflate, zstd)

--all-root

Make all files owned by root (UID/GID 0)

-L _label_

Set the volume label

-T _timestamp_

Use a fixed timestamp for all files (reproducible builds)

--exclude-path _pattern_

Exclude files matching the pattern

-E _options_

Extended options for fine-tuning

INSTALL

sudo apt install erofs-utils

sudo dnf install erofs-utils

sudo pacman -S erofs-utils

sudo apk add erofs-utils

sudo zypper install erofs-utils

brew install erofs-utils

nix profile install nixpkgs#erofs-utils

CAVEATS

EROFS is read-only; the source directory is not modified. Large directories may take time to process with compression enabled. Kernel support (CONFIGEROFSFS) is required to mount images. Best suited for scenarios where data doesn't change after creation.

HISTORY

EROFS was developed by Huawei and merged into the Linux kernel in version 4.19 (2018). It has since been adopted by Android for system partitions and various embedded Linux distributions.