path: root/doc/git-annex.mdwn

# NAME

git-annex - manage files with git, without checking their contents in

# SYNOPSIS

git annex subcommand [params ...]

# DESCRIPTION

git-annex allows managing files with git, without checking the file
contents into git. While that may seem paradoxical, it is useful when
dealing with files larger than git can currently easily handle, whether due
to limitations in memory, checksumming time, or disk space.

Even without file content tracking, being able to manage files with git,
move files around and delete files with versioned directory trees, and use
branches and distributed clones, are all very handy reasons to use git. And
annexed files can co-exist in the same git repository with regularly
versioned files, which is convenient for maintaining documents, Makefiles,
etc that are associated with annexed files but that benefit from full
revision control.

When a file is annexed, its content is moved into a key-value store, and
a symlink is made that points to the content. These symlinks are checked into
git and versioned like regular files. You can move them around, delete 
them, and so on. Pushing to another git repository will make git-annex
there aware of the annexed file, and it can be used to retrieve its
content from the key-value store.

# EXAMPLES

	# git annex get video/hackity_hack_and_kaxxt.mov
	get video/_why_hackity_hack_and_kaxxt.mov (not available)
	  I was unable to access these remotes: server
	  Try making some of these repositories available:
	  	5863d8c0-d9a9-11df-adb2-af51e6559a49  -- my home file server
	   	58d84e8a-d9ae-11df-a1aa-ab9aa8c00826  -- portable USB drive
	   	ca20064c-dbb5-11df-b2fe-002170d25c55  -- backup SATA drive
	failed
	# sudo mount /media/usb
	# git remote add usbdrive /media/usb
	# git annex get video/hackity_hack_and_kaxxt.mov
	get video/hackity_hack_and_kaxxt.mov (copying from usbdrive...) ok
	# git commit -a -m "got a video I want to rewatch on the plane"
	
	# git annex add iso
	add iso/Debian_5.0.iso ok
	# git commit -a -m "saving Debian CD for later"
	
	# git annex drop iso/Debian_4.0.iso
	drop iso/Debian_4.0.iso ok
	# git commit -a -m "freed up space"
	
	# git annex move iso --to=usbdrive
	move iso/Debian_5.0.iso (moving to usbdrive...) ok

# SUBCOMMANDS

Like many git commands, git-annex can be passed a path that 
is either a file or a directory. In the latter case it acts on all relevant
files in the directory.

Many git-annex subcommands will stage changes for later `git commit` by you.

* add [path ...]

  Adds files in the path to the annex. Files that are already checked into
  git, or that git has been configured to ignore will be silently skipped.

* get [path ...]

  Makes the content of annexed files available in this repository. Depending
  on the backend used, this will involve copying them from another repository,
  or downloading them, or transferring them from some kind of key-value store.

* drop [path ...]

  Drops the content of annexed files from this repository. 

  git-annex may refuse to drop content if the backend does not think
  it is safe to do so, typically because of the setting of annex.numcopies.

* unlock [path ...]

  Normally, the content of annexed files is protected from being changed.
  Unlocking a annexed file allows it to be modified. This replaces the
  symlink for each specified file with a copy of the file's content.
  You can then modify it and `git annex add` (or `git commit`) to inject
  it back into the annex.

* edit [path ...]

  This is an alias for the unlock subcommand. May be easier to remember,
  if you think of this as allowing you to edit an annexed file.

* move [path ...]

  When used with the --to option, moves the content of annexed files from
  the current repository to the specified one.

  When used with the --from option, moves the content of annexed files
  from the specified repository to the current one.

* init description

  Initializes git-annex with a description of the git repository,
  and sets up `.gitattributes` and the pre-commit hook.

* lock [path ...]

  Use this to undo an unlock command if you don't want to modify
  the files, or have made modifications you want to discard.

* fsck [path ...]

  With no parameters, this subcommand checks the whole annex for consistency,
  and warns about any problems found.

  With parameters, only the specified files are checked.

* unused

  Checks the annex for data that is not used by any files currently
  in the annex, and prints a numbered list of the data. 

* dropunused [number ...]

  Drops the data corresponding to the numbers, as listed by the last
  `git annex unused`

* find [path ...]

  Outputs a list of annexed files whose content is currently present.

  With no parameters, defaults to finding all files in the current directory
  and its subdirectories.

* unannex [path ...]

  Use this to undo an accidental add command. This is not the command you
  should use if you intentionally annexed a file and don't want its contents
  any more. In that case you should use `git annex drop` instead, and you
  can also `git rm` the file.

* fix [path ...]

  Fixes up symlinks that have become broken to again point to annexed content.
  This is useful to run if you have been moving the symlinks around.

* pre-commit [path ...]

  Fixes up symlinks that are staged as part of a commit, to ensure they
  point to annexed content. Also handles injecting changes to unlocked
  files into the annex.

  This is meant to be called from git's pre-commit hook. `git annex init`
  automatically creates a pre-commit hook using this.

* fromkey file

  This can be used to maually set up a file to link to a specified key
  in the key-value backend. How you determine an existing key in the backend
  varies. For the URL backend, the key is just a URL to the content.

  Example:

	git annex fromkey --backend=URL --key=http://www.archive.org/somefile somefile

* dropkey [key ...]

  This plumbing-level command drops the annexed data for the specified
  keys from this repository.

  This can be used to drop content for arbitrary keys, which do not need
  to have a file in the git repository pointing at them.

  A backend will typically need to be specified with --backend. If none
  is specified, the first configured backend is used.

  Example:

	git annex dropkey --backend=SHA1 7da006579dd64330eb2456001fd01948430572f2

* setkey file

  This plumbing-level command sets the annxed data for a key to the content of
  the specified file, and then removes the file.

  A backend will typically need to be specified with --backend. If none
  is specified, the first configured backend is used.

  Example:

	git annex setkey --backend=WORM --key=1287765018:3 /tmp/file

# OPTIONS

* --force

  Force unsafe actions, such as dropping a file's content when no other
  source of it can be verified to still exist. Use with care.

* --quiet

  Avoid the default verbose logging of what is done; only show errors
  and progress displays.

* --verbose

  Enable verbose logging.

* --from=repository

  Specifies a repository that content will be retrieved from.
  It should be specified using the name of a configured git remote.

* --to=repository

  Specifies a git repository that content will be sent to. 
  It should be specified using the name of a configured git remote.

* --backend=name

  Specifies which key-value backend to use.

* --key=name

  Specifies a key to operate on.

# CONFIGURATION

Like other git commands, git-annex is configured via `git-config`.
Here are all the supported configuration settings.

* `annex.uuid` -- a unique UUID for this repository (automatically set)
* `annex.numcopies` -- number of copies of files to keep across all
  repositories (default: 1)
* `annex.backends` -- space-separated list of names of 
  the key-value backends to use. The first listed is used to store
  new files by default. (default: "WORM SHA1 URL")
* `remote.<name>.annex-cost` -- When determining which repository to
  transfer annexed files from or to, ones with lower costs are preferred.
  The default cost is 100 for local repositories, and 200 for remote
  repositories.
* `remote.<name>.annex-ignore` -- If set to `true`, prevents git-annex
  from ever using this remote. This is, for example, useful if the
  remote is a bare repository, which git-annex does not currently support.
* `remote.<name>.annex-uuid` -- git-annex caches UUIDs of repositories
  here.
* `remote.<name>.annex-scp-options` -- Options to use when using scp
  to or from this repository. For example, to force ipv6, and limit
  the bandwidth to 100Kbit/s, set it to "-6 -l 100"
* `remote.<name>.annex-ssh-options` -- Options to use when using ssh
  to talk to this repository.
* `annex.scp-options` and `annex.ssh-options` -- Default scp and ssh
  options to use if a remote does not have specific options.
* `annex.version` -- Automatically maintained, and used to automate upgrades
  between versions.

The backend used when adding a new file to the annex can be configured
on a per-file-type basis via the `.gitattributes` file. In the file,
the `git-annex-backend` attribute can be set to the name of the backend to
use. For example, this here's how to use the WORM backend by default,
but the SHA1 backend for ogg files:

	* git-annex-backend=WORM
	*.ogg git-annex-backend=SHA1

# FILES

These files are used, in your git repository:

`.git/annex/objects/` contains the annexed file contents that are currently
available. Annexed files in your git repository symlink to that content.

`.git-annex/uuid.log` is used to map between repository UUID and
decscriptions. You may edit it.

`.git-annex/*.log` is where git-annex records its content tracking
information. These files should be committed to git.

`.gitattributes` is configured to use git's union merge driver
to avoid conflicts when merging files in the `.git-annex` directory.

# SEE ALSO

Most of git-annex's documentation is available on its web site, 
<http://git-annex.branchable.com/>

If git-annex is installed from a package, a copy of its documentation
should be included, in, for example, `/usr/share/doc/git-annex/`

# AUTHOR

Joey Hess <joey@kitenet.net>

<http://git-annex.branchable.com/>

Warning: this page is automatically made into a man page via [mdwn2man](http://git.ikiwiki.info/?p=ikiwiki;a=blob;f=mdwn2man;hb=HEAD).  Edit with care