Filesystem in Userspace

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Filesystem in Userspace
Stable release
3.2.4 / 11 July 2018; 4 months ago (2018-07-11)[1]
Repository Edit this at Wikidata
Written inC
Operating systemUnix-like
TypeFile system driver
LicenseGPL for kernel part, LGPL for Libfuse, Simplified BSD on FreeBSD, ISC license on OpenBSD

Filesystem in Userspace (FUSE) is a software interface for Unix-like computer operating systems that lets non-privileged users create their own file systems without editing kernel 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, FreeBSD, OpenBSD, NetBSD (as puffs), OpenSolaris, Minix 3, Android and macOS.[2]

FUSE is free software originally released under the terms of the GNU General Public License and the GNU Lesser General Public License.


The FUSE system was originally part of AVFS (A Virtual Filesystem), a filesystem implementation heavily influenced by the translator concept of the GNU Hurd.[3]

FUSE was originally released under the terms of the GNU General Public License and the GNU Lesser General Public License, later also reimplemented as part of the FreeBSD base system[4] and released under the terms of Simplified BSD license. An ISC-licensed re-implementation by Sylvestre Gallon was released in March 2013,[5] and incorporated into OpenBSD in June 2013.[6]

FUSE was merged into the mainstream Linux kernel tree in kernel version 2.6.14.[7]

A flow-chart diagram showing how FUSE works: Request from userspace to list files (ls -l /tmp/fuse) gets redirected by the Kernel through VFS to FUSE. FUSE then executes the registered handler program (./hello) and passes it the request (ls -l /tmp/fuse). The handler program returns a response back to FUSE which is then redirected to the userspace program that originally made the request.

Operation and Uses[edit]

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.

Unmounting a FUSE-based file system with the fusermount command

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.

Example uses[edit]

  • archivemount
  • CloudStore (formerly, Kosmos filesystem): By mounting via FUSE, existing Linux utilities can interact with CloudStore
  • EncFS: Encrypted virtual filesystem
  • ExpanDrive: A commercial filesystem implementing SFTP/FTP/S3/Swift using FUSE
  • GlusterFS: Clustered Distributed Filesystem having ability to scale up to several petabytes.
  • GmailFS: Filesystem which stores data as mail in Gmail
  • GVfs: The virtual filesystem for the GNOME desktop
  • KBFS: A distributed filesystem with end-to-end encryption and a global namespace based on 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.[8] However, the ZFS-Linux port of Lustre will be running ZFS's DMU (Data Management Unit) in userspace.[9]
  • MinFS: MinFS is a fuse driver for Amazon S3 compatible object storage server. MinFS[10] 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.
  • NTFS-3G and Captive NTFS, allowing access to NTFS filesystems
  • 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: View and edit Wikipedia articles as if they were real files
  • Wuala: A multi-platform, Java-based fully OS integrated distributed file system. Using FUSE, MacFUSE and Callback File System respectively for file system integration, in addition to a Java-based app accessible from any Java-enabled web browser (service discontinued in 2015).

See also[edit]


  1. ^ "Releases - libfuse/libfuse". Retrieved 11 July 2018 – via GitHub.
  2. ^ "Home - FUSE for OS X".
  3. ^ "Some technical advantages of the Hurd". May 15, 2011. Retrieved March 28, 2016.
  4. ^ "WhatsNew/FreeBSD10 - FreeBSD Wiki".
  5. ^ "openbsd dev - tech - Fuse (and sshfs) support for OpenBSD".
  6. ^ "'CVS: src' - MARC".
  7. ^ "file-systems.fuse.devel - FUSE merged to 2.6.14! - msg#00021 - Recent Discussion". Archived from the original on 2016-04-20.
  8. ^ "Lustre FreeBSD". Archived from the original on 2008-03-12. Retrieved 2008-03-02.
  9. ^ "Architecture ZFS for Lustre". Sun Microsystems. Retrieved 2008-03-02.
  10. ^ "minio/minfs". GitHub. Retrieved 12 April 2018.

External links[edit]