git-annex-export(1)

NAME
git-annex-export - export a tree of files to a special remote

SYNOPSIS
git annex export treeish --to remote

DESCRIPTION
Use this command to export a tree of files from a git-annex repository.

Normally files are stored on a git-annex special remote named by their keys. That is great for reliable data storage, but your filenames are obscured. Exporting replicates the tree to the special remote as-is.

To use this, you have to configure a special remote with exporttree=yes when initially setting it up with git-annex-initremote(1).

The treeish to export can be the name of a git branch, or a tag, or any other treeish accepted by git, including eg master:subdir to only export a subdirectory from a branch.

When the remote has a preferred content expression set by git-annex-wanted(1), the treeish is filtered through it, excluding annexed files it does not want from being exported to it. (Note that things in the expression like "include=" match relative to the top of the treeish being exported.)

Any files in the treeish that are stored on git will also be exported to the special remote.

Repeated exports are done efficiently, by diffing the old and new tree, and transferring only the changed files, and renaming files as necessary.

Exports can be interrupted and resumed. However, partially uploaded files will be re-started from the beginning in most cases.

Once content has been exported to a remote, commands like git annex get can download content from there the same as from other remotes. However, since an export is not a key/value store, git-annex has to do more verification of content downloaded from an export. Some types of keys, that are not based on checksums, cannot be downloaded from an export. And, git-annex will never trust an export to retain the content of a key.

However, some special remotes, notably S3, support keeping track of old versions of files stored in them. If a special remote is set up to do that, it can be used as a key/value store and the limitations in the above paragraph do not apply. Note that dropping content from such a remote is not supported. See individual special remotes' documentation for details of how to enable such versioning.

Commands like git-annex push can also be used to export a branch to a special remote, updating the special remote whenever the branch is changed. To do this, you need to configure "remote.<name>.annex-tracking-branch" to tell it what branch to track. For example:

 git config remote.myremote.annex-tracking-branch master
 git annex push myremote

When the special remote is not also configured with importtree=yes, git-annex does not try to preserve other files that may be written to the special remote by other means. Exporting a tree of files to a special remote will overwrite any files already stored on it with the same filenames. In some cases, an update to what is exported that deletes a subdirectory will delete not only the exported files that were in that subdirectory, but any other files that might have been written to the same subdirectory by other means.

When the special remote is also configured with importtree=yes, you can combine using git annex export to send changes to a special remote with git annex import to fetch changes from a special remote. In this case, when a file on a special remote has been modified by software other than git-annex, exporting to it will not overwrite the modified file, and the export will not succeed. You can resolve this conflict by using git annex import.

(Some types of special remotes such as S3 with versioning may instead let an export overwrite the modified file; then git annex import will create a sequence of commits that includes the modified file, so the overwritten modification is not lost.)

OPTIONS

--to=remote

    Specify the special remote to export to.

--from=remote
    When the content of a file is not available in the local repository, this option lets it be downloaded from another remote, and sent on to the destination remote. The file will be temporarily stored on local disk, but will never enter the local repository.

    This option can be repeated multiple times.

    It is possible to use --from with the same remote as --to. If the tree contains several files with the same content, and the remote being exported to already contains one copy of the content, this allows making a copy by downloading the content from it.

--tracking
    This is a deprecated way to set "remote.<name>.annex-tracking-branch". Instead of using this option, you should just set the git configuration yourself.

--fast
    This sets up an export of a tree, but avoids any expensive file uploads to the remote. You can later run git annex push to upload the files to the export.

--jobs=N -JN
    Exports multiple files in parallel. This may be faster. For example: -J4

    Setting this to "cpus" will run one job per CPU core.

--json
    Enable JSON output. This is intended to be parsed by programs that use git-annex. Each line of output is a JSON object.

--json-progress
    Include progress objects in JSON output.

--json-error-messages
    Messages that would normally be output to standard error are included in the JSON instead.

Also the git-annex-common-options(1) can be used.

EXAMPLE
 git annex initremote myremote type=directory directory=/mnt/myremote \
     exporttree=yes encryption=none
 git annex export master --to myremote

After that, /mnt/myremote will contain the same tree of files as the master branch does.

 git mv myfile subdir/myfile
 git commit -m renamed
 git annex export master --to myremote

That updates /mnt/myremote to reflect the renamed file.

 git annex export master:subdir --to myremote

That updates /mnt/myremote, to contain only the files in the "subdir" directory of the master branch.

EXPORT CONFLICTS
If two different git-annex repositories are both exporting different trees to the same special remote, it's possible for an export conflict to occur. This leaves the special remote with some files from one tree, and some files from the other. Files in the special remote may have entirely the wrong content as well.

It's not possible for git-annex to detect when making an export will result in an export conflict. The best way to avoid export conflicts is to either only ever export to a special remote from a single repository, or to have a rule about the tree that you export to the special remote. For example, if you always export origin/master after pushing to origin, then an export conflict can't happen.

An export conflict can only be detected after the two git repositories that produced it get back in sync. Then the next time you run git annex export, it will detect the export conflict, and resolve it.

SEE ALSO
git-annex(1)

git-annex-initremote(1)

git-annex-import(1)

git-annex-push(1)

git-annex-preferred-content(1)

HISTORY
The export command was introduced in git-annex version 6.20170925.

AUTHOR
Joey Hess <id@joeyh.name>