Normally, git-annex stores annexed files in the repository, locked down, which prevents the content of the file from being modified. That's a good thing, because it might be the only copy, you wouldn't want to lose it in a fumblefingered mistake. # git annex add some_file add some_file # echo oops > some_file bash: some_file: Permission denied Sometimes though you want to modify a file. Maybe once, or maybe repeatedly. To support this, git-annex also supports unlocked files. They are stored in the git repository differently, and they appear as regular files in the working tree, instead of the symbolic links used for locked files. ## adding unlocked files Instead of using `git annex add`, use `git add`, and the file will be stored in git-annex, but left unlocked. [[!template id=note text=""" Want `git add` to add some file contents to the annex, but store the contents of smaller files in git itself? Configure annex.largefiles to match the former. See [[largefiles]]. """]] # cp ~/my_cool_big_file . # git add my_cool_big_file # git commit -m "added my_cool_big_file to the annex" [master (root-commit) 92f2725] added my_cool_big_file to the annex 1 file changed, 1 insertion(+) create mode 100644 my_cool_big_file # git annex find my_cool_big_file You can make whatever modifications you want to unlocked files, and commit your changes. # echo more stuff >> my_cool_big_file # git mv my_cool_big_file my_cool_bigger_file # git commit -a -m "some changes" [master 196c0e2] some changes 2 files changed, 1 insertion(+), 1 deletion(-) delete mode 100644 my_cool_big_file create mode 100644 my_cool_bigger_file Under the hood, this uses git's [[todo/smudge]] filter interface, and git-annex converts between the content of the big file and a pointer file, which is what gets committed to git. All the regular git-annex commands (get, drop, etc) can be used on unlocked files too. [[!template id=note text=""" By default, git-annex commands will add files in locked mode, unless used on a filesystem that does not support symlinks, when unlocked mode is used. To make them always use unlocked mode, run: `git config annex.addunlocked true` """]] ## mixing locked and unlocked files A repository can contain both locked and unlocked files. You can switch a file back and forth using the `git annex lock` and `git annex unlock` commands. This changes what's stored in git between a git-annex symlink (locked) and a git-annex pointer file (unlocked). To add a file to the repository in locked mode, use `git annex add`; to add a file in unlocked mode, use `git add`. If you want to mostly keep files locked, but be able to locally switch to having them all unlocked, you can do so using `git annex adjust --unlock`. See [[git-annex-adjust]] for details. This is particularly useful when using filesystems like FAT, and OS's like Windows that don't support symlinks. Indeed, `git-annex init` detects such filesystems and automatically sets up a repository to use all unlocked files. ## imperfections Unlocked files mostly work very well, but there are a few imperfections which you should be aware of when using them. 1. `git stash`, `git cherry-pick` and `git reset --hard` don't update the working tree with the content of unlocked files. The files will contain pointers, the same as if the content was not in the repository. So after running these commands, you will need to manually run `git annex smudge --update`. 2. When git-annex is running a command that gets or drops the content of an unlocked file, git's index will briefly be locked, which might prevent you from running a `git commit` at the same time. 3. Conversely, if you have a git commit in progress, running git-annex may complain that the index is locked, though this will not prevent it from working. 4. When an operation such as a checkout or merge needs to update a large number of unlocked files, it can become slow. So can be `git add` of a large number of files (`git annex add` is faster). (The technical reasons behind these imperfections are explained in detail in [[todo/git_smudge_clean_interface_suboptiomal]].) ## using less disk space Unlocked files are handy, but they have one significant disadvantage compared with locked files: They use more disk space. While only one copy of a locked file has to be stored, often two copies of an unlocked file are stored on disk. One copy is in the git work tree, where you can use and modify it, and the other is stashed away in `.git/annex/objects` (see [[internals]]). The reason for that second copy is to preserve the old version of the file, when you modify the unlocked file in the work tree. Being able to access old versions of files is an important part of git after all! That's a good safe default. But there are ways to use git-annex that make the second copy not be worth keeping: * When you're using git-annex to sync the current version of files across devices, and don't care much about previous versions. * When you have set up a backup repository, and use git-annex to copy your files to the backup. In situations like these, you may want to avoid the overhead of the second local copy of unlocked files. There's a config setting for that. [[!template id=note text=""" Note that setting annex.thin only has any effect on systems that support hard links. It is supported on Windows, but not on FAT filesystems. """]] git config annex.thin true After changing annex.thin, you'll want to fix up the work tree to match the new setting: git annex fix [[!template id=note text=""" When a [[direct_mode]] repository is upgraded, annex.thin is automatically set, because direct mode made the same single-copy tradeoff. """]] Setting annex.thin can save a lot of disk space, but it's a tradeoff between disk usage and safety. Keeping files locked is safer and also avoids using unnecessary disk space, but trades off easy modification of files. Pick the tradeoff that's right for you.