btrgit/README.template at master · facetframer/btrgit · GitHub

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# btrgit

Interact with [btrfs](https://btrfs.wiki.kernel.org/index.php/Main_Page) snapshots made with [snapper](http://snapper.io/documentation.html) in a manner reminiscent of [git](https://git-scm.com/).

Search for changes to files and restore old versions of files. The output is designed to be useable by other command line tools.

Written and maintained by [Facet](https://www.facetframer.com/).

# Attribution

Adapted from [answers of server fault](http://serverfault.com/questions/399894/does-btrfs-have-an-efficient-way-to-compare-snapshots).


# Installing

```
pip install git+https://github.com/talwrii/btrgit#egg=btrgit
```

# Examples / Cheat sheet

```
# Show what changes have recently happened to home
btrgit log /home

# Show what changed in snapshot 443
btrgit log /home 443

```

# Usage

```
{usage}
```

# Discussion

[btrfs](https://btrfs.wiki.kernel.org/index.php/Main_Page) is an [open-source](https://opensource.org/) filesystem for the [linux](https://www.kernel.org/linux.html) operating system. Btrfs provides a feature called copy-on-write which allows files to be copied at virtual zero cost in terms of time and storage (see [Functional Data Structure](https://en.wikipedia.org/wiki/Purely_functional_data_structure).

This feature also allows the implementation of *snapshots*, complete copies filesystem at a particular point in time at very little cost. Snapshots have existing in other filesystems and surrounding utilities: notably [lvm](http://tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html), but the performance benefits of copy-on-write allows snapshots to be used far more aggressively.

[snapper](http://snapper.io/documentation.html) is one such tool that takes advantages of snapshots to produce an ordered history of how a filesystem has change.

The author found that he desired a more feature-complete interface to this history, and noting the similarity of of this concept to version control systems like [git](https://git-scm.com/) decided to write an interface more reminiscent of git.

# Alternatives and prior work

- An initial subset of features was adapted from [answers of server fault](http://serverfault.com/questions/399894/does-btrfs-have-an-efficient-way-to-compare-snapshots).
- This ideas here very much represents [snapper's](http://snapper.io/documentation.html) existing feature through the metaphor of  [git](https://git-scm.com/)
- https://github.com/sysnux/btrfs-snapshots-diff.git was a pre-existing project to see the difference between btrfs snapshots
- [snapper gui](https://github.com/ricardomv/snapper-gui) is a gui which may well provide similar features.
- [zfs](https://docs.oracle.com/cd/E19253-01/819-5461/zfsover-2/index.html) is an open-source copy-on-write filesystem with similar features to btrfs that is used in production by various companies. Code for zfs is owned by Oracle. [Oracle has sued google using its copyright claims on another peice of open-source: Java](https://www.cnet.com/news/oracle-sues-google-over-android-and-java/). There is an (at the time of writing open) [issue for extending snapper to interact with zfs](https://github.com/openSUSE/snapper/issues/145)
)


Influenced by `git`

# Caveats

- This approach uses `btrfs subvolumes find-new`, there is an alternative approach using `btrfs receive`.