git-sparse-checkout

git-sparse-checkout - Initialize and modify the sparse-checkout configuration, which reduces the checkout to a set of paths given by a list of patterns.

Initialize and modify the sparse-checkout configuration, which reduces the checkout to a set of paths given by a list of patterns.

THIS COMMAND IS EXPERIMENTAL. ITS BEHAVIOR, AND THE BEHAVIOR OF OTHER COMMANDS IN THE PRESENCE OF SPARSE-CHECKOUTS, WILL LIKELY CHANGE IN THE FUTURE.

"Sparse checkout" allows populating the working directory sparsely. It uses the skip-worktree bit (see git-update-index[1]) to tell Git whether a file in the working directory is worth looking at. If the skip-worktree bit is set, then the file is ignored in the working directory. Git will not populate the contents of those files, which makes a sparse checkout helpful when working in a repository with many files, but only a few are important to the current user.

The $GIT_DIR/info/sparse-checkout file is used to define the skip-worktree reference bitmap. When Git updates the working directory, it updates the skip-worktree bits in the index based on this file. The files matching the patterns in the file will appear in the working directory, and the rest will not.

To enable the sparse-checkout feature, run git sparse-checkout init to initialize a simple sparse-checkout file and enable the core.sparseCheckout config setting. Then, run git sparse-checkout set to modify the patterns in the sparse-checkout file.

To repopulate the working directory with all files, use the git sparse-checkout disable command.

By default, the sparse-checkout file uses the same syntax as .gitignore files.

While $GIT_DIR/info/sparse-checkout is usually used to specify what files are included, you can also specify what files are not included, using negative patterns. For example, to remove the file unwanted:

/*
!unwanted

The full pattern set allows for arbitrary pattern matches and complicated inclusion/exclusion rules. These can result in O(N*M) pattern matches when updating the index, where N is the number of patterns and M is the number of paths in the index. To combat this performance issue, a more restricted pattern set is allowed when core.sparseCheckoutCone is enabled.

The accepted patterns in the cone pattern set are:

In addition to the above two patterns, we also expect that all files in the root directory are included. If a recursive pattern is added, then all leading directories are added as parent patterns.

By default, when running git sparse-checkout init, the root directory is added as a parent pattern. At this point, the sparse-checkout file contains the following patterns:

/*
!/*/

This says "include everything in root, but nothing two levels below root."

When in cone mode, the git sparse-checkout set subcommand takes a list of directories instead of a list of sparse-checkout patterns. In this mode, the command git sparse-checkout set A/B/C sets the directory A/B/C as a recursive pattern, the directories A and A/B are added as parent patterns. The resulting sparse-checkout file is now

/*
!/*/
/A/
!/A/*/
/A/B/
!/A/B/*/
/A/B/C/

Here, order matters, so the negative patterns are overridden by the positive patterns that appear lower in the file.

If core.sparseCheckoutCone=true, then Git will parse the sparse-checkout file expecting patterns of these types. Git will warn if the patterns do not match. If the patterns do match the expected format, then Git will use faster hash- based algorithms to compute inclusion in the sparse-checkout.

In the cone mode case, the git sparse-checkout list subcommand will list the directories that define the recursive patterns. For the example sparse-checkout file above, the output is as follows:

$ git sparse-checkout list
A/B/C

If core.ignoreCase=true, then the pattern-matching algorithm will use a case-insensitive check. This corrects for case mismatched filenames in the git sparse-checkout set command to reflect the expected cone in the working directory.

When changing the sparse-checkout patterns in cone mode, Git will inspect each tracked directory that is not within the sparse-checkout cone to see if it contains any untracked files. If all of those files are ignored due to the .gitignore patterns, then the directory will be deleted. If any of the untracked files within that directory is not ignored, then no deletions will occur within that directory and a warning message will appear. If these files are important, then reset your sparse-checkout definition so they are included, use git add and git commit to store them, then remove any remaining files manually to ensure Git can behave optimally.

If your repository contains one or more submodules, then submodules are populated based on interactions with the git submodule command. Specifically, git submodule init -- <path> will ensure the submodule at <path> is present, while git submodule deinit [-f] -- <path> will remove the files for the submodule at <path> (including any untracked files, uncommitted changes, and unpushed history). Similar to how sparse-checkout removes files from the working tree but still leaves entries in the index, deinitialized submodules are removed from the working directory but still have an entry in the index.

Since submodules may have unpushed changes or untracked files, removing them could result in data loss. Thus, changing sparse inclusion/exclusion rules will not cause an already checked out submodule to be removed from the working copy. Said another way, just as checkout will not cause submodules to be automatically removed or initialized even when switching between branches that remove or add submodules, using sparse-checkout to reduce or expand the scope of "interesting" files will not cause submodules to be automatically deinitialized or initialized either.

Further, the above facts mean that there are multiple reasons that "tracked" files might not be present in the working copy: sparsity pattern application from sparse-checkout, and submodule initialization state. Thus, commands like git grep that work on tracked files in the working copy may return results that are limited by either or both of these restrictions.

git-read-tree[1] gitignore[5]