git-annex/doc/direct_mode.mdwn

Normally, git-annex repositories consist of symlinks that are checked into
git, and in turn point at the content of large files that is stored in
`.git/annex/objects/`. Direct mode gets rid of the symlinks.

The advantage of direct mode is that you can access files directly,
including modifying them. The disadvantage is that most regular git
commands cannot safely be used, and only a subset of git-annex commands
can be used.

Normally, git-annex repositories start off in indirect mode. With some
exceptions:

* Repositories created by the [[assistant]] use direct mode by default.
* Repositories on FAT and other less than stellar filesystems
  that don't support things like symlinks will be automatically put
  into direct mode.

## enabling (and disabling) direct mode

Any repository can be converted to use direct mode at any time, and if you
decide not to use it, you can convert back to indirect mode just as easily.
Also, you can have one clone of a repository using direct mode, and another
using indirect mode; direct mode interoperates.

To start using direct mode:

	git annex direct

To stop using direct mode:

	git annex indirect

## safety of using direct mode

With direct mode, you're operating without large swathes of git-annex's
carefully constructed safety net, which ensures that past versions of
files are preserved and can be accessed (until you dropunused them). 
With direct mode, any file can be edited directly, or deleted at any time,
and there's no guarantee that the old version is backed up somewhere else.

So if you care about preserving the history of files, you're strongly
encouraged to tell git-annex that your direct mode repository cannot be
trusted to retain the content of a file. To do so:

	git annex untrust .

On the other hand, if you only care about the current versions of files,
and are using git-annex with direct mode to keep files synchronised between
computers, and manage your files, this should not be a concern for you.

## use a direct mode repository

You can use most git-annex commands as usual in a direct mode repository.
A very few commands don't work in direct mode, and will refuse to do anything.

Direct mode also works well with the git-annex assistant.

You can use `git commit --staged`, or plain `git commit`.
But not `git commit -a`, or `git commit <file>` ..
that'd commit whole large files into git!

## what doesn't work in direct mode

`git annex status` shows incomplete information. A few other commands,
like `git annex unlock` don't make sense in direct mode and will refuse to
run.

As for git commands, you can probably use some git working tree
manipulation commands, like `git checkout` and `git revert` in useful
ways... But beware, these commands can replace files that are present in
your repository with broken symlinks. If that file was the only copy you
had of something, it'll be lost. 

This is one more reason it's wise to make git-annex untrust your direct mode
repositories. Still, you can lose data using these sort of git commands, so
use extreme caution.