git-annex/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 push usbdrive iso
	error: push not yet implemented!
	# git annex drop iso
	drop iso/Debian_5.0.iso ok
	# git commit -a -m "freed up space"

# 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 a content if the backend does not think
  it is safe to do so. 

* 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.

* init description

  Initializes git-annex with a descripotion of the git repository.
  This is an optional, but recommended step.

* 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.

* 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

# 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.

* --backend=name

  Specify the default key-value backend to use, adding it to the front
  of the list normally configured by `annex.backends`.

* --key=name

  Specifies a key to operate on, for use with the addkey subcommand.

## CONFIGURATION

Like other git commands, git-annex is configured via `.git/config`.

* `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. (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. Note that other factors may be configured when pushing
  files to repositories, in particular, whether the repository is on
  a filesystem with sufficient free space.
* `remote.<name>.annex-uuid` -- git-annex caches UUIDs of repositories
  here.

# FILES

These files are used, in your git repository:

`.git/annex/` 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.

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

# AUTHOR

Joey Hess <joey@ikiwiki.info>

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

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