Editing UnionFS (section)

==Uses==
In [[Knoppix]], a union between the file system on the [[CD-ROM]] or [[DVD]] and a file system contained in an image file called ''knoppix.img'' (knoppix-data.img for Knoppix 7) on a writable drive (such as a [[USB memory stick]]) can be made, where the writable drive has priority over the read-only filesystem. This allows the user to change any of the files on the system, with the new file stored in the image and transparently used instead of the one on the CD.<ref>{{cite web
| url = http://knoppix.net/wiki/Category:Hard_drive_Installation#UNIONFS
| title = Hard drive Installation: UNIONFS
| first = Werner P.
| last = Schulz
| date = 2016-12-15
| publisher = [[Knoppix]]
| access-date = 2017-07-17}}</ref>

Unionfs can also be used to create a single common template for a number of file systems, or for security reasons. It is sometimes used as an ''ad hoc'' [[snapshot (computer storage)|snapshot]]ting system.

[[Docker (software)|Docker]] uses file systems inspired by Unionfs, such as [[Aufs]], to layer Docker images. As actions are done to a base image, layers are created and documented, such that each layer fully describes how to recreate an action. This strategy enables Docker's lightweight images, as only layer updates need to be propagated (compared to full VMs, for example).<ref>{{cite web
| url=https://docs.docker.com/engine/docker-overview/#union-file-systems
| title=Docker overview: Union file systems
| date=2017-07-13
| publisher=[[Docker, Inc.]]
| access-date=2017-07-17}}</ref>

''UbuntuLTSP'', the Linux Terminal Server Project implementation for Ubuntu, uses Unionfs when PXE booting thin or thick clients.<ref>{{cite web
| url=https://help.ubuntu.com/community/UbuntuLTSP/LTSPWithoutNFS
| title=UbuntuLTSP/LTSPWithoutNFS
| first=Alkis
| last=Georgopoulos
| date=2010-12-24
| access-date=2017-07-17}}</ref>