Filesystem in Userspace (FUSE) is a software interface for

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

and

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computer

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

s that lets non-privileged users create their own

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one lar ...

s without editing

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine lea ...

code. This is achieved by running file system code in user space while the FUSE module provides only a bridge to the actual kernel interfaces. FUSE is available for

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

, FreeBSD,

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, NetBSD (as puffs),

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, Minix 3,

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, and

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. FUSE is

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originally released under the terms of the

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and the GNU Lesser General Public License.

History

The FUSE system was originally part of ''AVFS'' (''A Virtual Filesystem''), a filesystem implementation heavily influenced by the translator concept of the GNU Hurd. It superseded Linux Userland Filesystem, and provided a translational interface using in libfuse1. FUSE was originally released under the terms of the

and the GNU Lesser General Public License, later also reimplemented as part of the FreeBSD base system and released under the terms of Simplified BSD license. An ISC-licensed re-implementation by Sylvestre Gallon was released in March 2013, and incorporated into

in June 2013. FUSE was merged into the mainstream

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

tree in kernel version 2.6.14. The userspace side of FUSE, the library, generally followed the pace of Linux kernel development while maintaining "best effort" compatibility with BSD descendants. This is possible because the kernel FUSE reports its own "feature levels", or versions. The exception is the FUSE fork for macOS, OSXFUSE, which has too many differences for sharing a library. A break in libfuse history is libfuse3, which includes some incompatible improvements in the interface and performance, compared to the older libfuse2 now under maintenance mode. As the kernel-userspace protocol of FUSE is versioned and public, a programmer can choose to use a different piece of code in place of and still communicate with the kernel's FUSE facilities. On the other hand, and its many ports provide a portable high-level interface that may be implemented on a system without a "FUSE" facility.

Operation and usage

To implement a new file system, a handler program linked to the supplied libfuse library needs to be written. The main purpose of this program is to specify how the file system is to respond to read/write/stat requests. The program is also used to mount the new file system. At the time the file system is mounted, the handler is registered with the kernel. If a user now issues read/write/stat requests for this newly mounted file system, the kernel forwards these IO-requests to the handler and then sends the handler's response back to the user. Unmount SSHFS

FUSE is particularly useful for writing virtual file systems. Unlike traditional file systems that essentially work with data on mass storage, virtual filesystems don't actually store data themselves. They act as a view or translation of an existing file system or storage device. In principle, any resource available to a FUSE implementation can be exported as a file system.

Applications

On-disk file systems

Conventional on-disk file systems can be implemented in user space with FUSE, e.g. for compatibility or licensing reasons. * Linear Tape File System: Allows files stored on magnetic tape to be accessed in a similar fashion to those on disk or removable flash drives. * NTFS-3G and

Captive NTFS Captive NTFS is a discontinued open-source project in the Linux programming community, started by Jan Kratochvíl. It is a driver wrapper around the original Microsoft Windows NTFS file system driver using parts of ReactOS code. By taking this app ...

, allowing access to NTFS filesystems.
retro-fuse
retro-fuse is a user-space filesystem that provides a way to mount filesystems created by ancient Unix systems on modern OSes. The current version of retro-fuse supports mounting filesystems created by Fifth, Sixth and Seventh Edition of Research Unix from BTL, as well as 2.9BSD and 2.11BSD based systems.

Layering file systems

FUSE filesystems can create a view of an underlying file system, transforming the files in some way. * EncFS: Encrypted virtual filesystem * FuseCompress, gzipfs, Fuse-ZIP, CompFUSEd: Compressed virtual filesystems * Archive filesystems may also perform this task

Archive and backup file systems

FUSE filesystems can expose the contents of archives or backup sets without having to first extract them. *

archivemount archivemount is a FUSE-based file system for Unix variants, including Linux. Its purpose is to mount archives (e.g. tar, tar.gz, etc.) to a mount point where it can be read from or written to as with any other file system. This makes accessing t ...

Atlas (Rubrik backup software)
Immutable, distributed filesystem used by Rubrik Cloud Data Management data protection applications * Borg (backup software): Deduplicating backup program that allows backup archives to be mounted as FUSE filesystems.
Restic
Free, fast, efficient and secure backup software uses FUSE to be able to browse all of your backup snapshots as a regular file system
SPFS
A file system for Spectrum Protect, designed to mount the backup server filespace anywhere on your server, and use the features included from the backup server ( encryption, de-duplication, compression, filtrering etc). This is a WORM file system.

Remote/distributed file system clients

CernVM-FS
A distributed read-only software distribution system, implemented as a POSIX filesystem in user space (FUSE) using HTTP transport, to deliver software in a fast and reliable fashion at global scale. * CloudStore (formerly, Kosmos filesystem): By mounting via FUSE, existing

utilities can interact with CloudStore * ExpanDrive: A commercial filesystem implementing SFTP/FTP/S3/Swift using FUSE * FTPFS * GlusterFS: Clustered Distributed Filesystem having ability to scale up to several petabytes.
goofys
A FUSE filesystem that allows access to Amazon S3/Microsoft Azure storage with an emphasis on performance.
google-drive-ocamlfuse
is a FUSE filesystem for Google Drive, written in OCaml. It lets you mount your Google Drive on Linux. * IPFS: A peer-to-peer distributed file system that seeks to connect all computing devices with the same system of files. * JuiceFS: A distributed POSIX file system built on top of Redis and S3. * KBFS: A distributed filesystem with end-to-end encryption and a global namespace based on Keybase.io service that uses FUSE to create cryptographically secure file mounts. * Lustre Cluster filesystem will use FUSE to allow it to run in userspace, so that a FreeBSD port is possible. However, the ZFS-Linux port of Lustre will be running ZFS's DMU (Data Management Unit) in userspace. * MinFS: MinFS is a fuse driver for Amazon S3 compatible object storage server. MinFS lets you mount a remote bucket (from a S3 compatible object store), as if it were a local directory. * MooseFS: An open source distributed fault-tolerant file system available on every OS with FUSE implementation (Linux, FreeBSD, NetBSD, OpenSolaris, OS X), able to store petabytes of data spread over several servers visible as one resource.
Nexfs
A commercial Linux file system that combines Block, File, and S3 compatible Cloud & Object storage into a single pool of POSIX compatible storage.
ObjectiveFS
Distributed filesystem with object store backend (Amazon S3, Google Cloud Storage or S3-compatible object store) using FUSE *

Rclone Rclone is an open source, multi threaded, command line computer program to manage or migrate content on cloud and other high latency storage. Its capabilities include sync, transfer, crypt, cache, union, compress and mount. The rclone web ...

can mount a variety of remote / cloud storage with FUSE.
s3fs
Gives the ability to mount an S3 bucket as if it were a local file system. * Sector File System: Sector is a distributed file system designed for large amount of commodity computers. Sector uses FUSE to provide a mountable local file system interface. * SSHFS: Provides access to a remote filesystem through SSH. * Transmit: A commercial FTP client that also adds the ability to mount WebDAV, SFTP, FTP and Amazon S3 servers as disks in Finder, via MacFUSE. * WebDrive: A commercial filesystem implementing WebDAV, SFTP, FTP, FTPS and Amazon S3 *

WikipediaFS WikipediaFS is a virtual filesystem which allows users to view and edit the articles of any MediaWiki-based site as if they were real files on a local disk drive. This enables a user to edit articles directly with any text editor. WikipediaFS is ...

: View and edit Wikipedia articles as if they were real files * Wuala: Was a multi-platform, Java-based fully OS integrated distributed file system. Using FUSE, MacFUSE an
CBFS Connect
respectively for file system integration, in addition to a Java-based app accessible from any Java-enabled web browser (service discontinued in 2015).
IndexFS
A remote file aggregating filesystem with transparent CURL access to distributed files.

Other

* GVfs: The virtual filesystem for the GNOME desktop
rvault
A secure and authenticated store for secrets and small documents using envelope encryption with one-time password (OTP) authentication. It uses FUSE to expose the vault as a file system.

References

External links

*
Develop your own filesystem with FUSE
by Sumit Singh
List of FUSE filesystemsDocumentation/filesystems/fuse.txt
documentation in Linux source tree
WinFSP
a FUSE-like system for Windows (a FUSE compatibility layer is provided for Cygwin)
Crossmeta FUSE
Port of FUSE to Windows (commercial software) {{Filesystem Free software programmed in C Free special-purpose file systems Linux kernel features Software that uses Meson Unix file system-related software Userspace file systems