git-sparse-checkout.txt

git-sparse-checkout(1)
======================

NAME
----
git-sparse-checkout - Reduce your working tree to a subset of tracked files


SYNOPSIS
--------
[verse]
'git sparse-checkout <subcommand> [<options>]'


DESCRIPTION
-----------

This command is used to create sparse checkouts, which means that it
changes the working tree from having all tracked files present, to only
have a subset of them.  It can also switch which subset of files are
present, or undo and go back to having all tracked files present in the
working copy.

The subset of files is chosen by providing a list of directories in
cone mode (which is recommended), or by providing a list of patterns
in non-cone mode.

When in a sparse-checkout, other Git commands behave a bit differently.
For example, switching branches will not update paths outside the
sparse-checkout directories/patterns, and `git commit -a` will not record
paths outside the sparse-checkout directories/patterns as deleted.

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


COMMANDS
--------
'list'::
	Describe the directories or patterns in the sparse-checkout file.

'set'::
	Enable the necessary config settings (extensions.worktreeConfig,
	core.sparseCheckout, core.sparseCheckoutCone, index.sparse) if
	they are not already enabled, and write a set of patterns to the
	sparse-checkout file from the list of arguments following the
	'set' subcommand. Update the working directory to match the new
	patterns.
+
When the `--stdin` option is provided, the directories or patterns are
read from standard in as a newline-delimited list instead of from the
arguments.
+
By default, the input list is considered a list of directories, matching
the output of `git ls-tree -d --name-only`.  This includes interpreting
pathnames that begin with a double quote (") as C-style quoted strings.
Note that all files under the specified directories (at any depth) will
be included in the sparse checkout, as well as files that are siblings
of either the given directory or any of its ancestors (see 'CONE PATTERN
SET' below for more details).  In the past, this was not the default,
and `--cone` needed to be specified or `core.sparseCheckoutCone` needed
to be enabled.
+
When `--no-cone` is passed, the input list is considered a list of
patterns.  This mode is harder to use, and unless you can keep the
number of patterns very small, its design also scales quite poorly.  It
used to be the default mode, but we do not recommend using it.  It does
not work with the `--sparse-index` option, and will likely be
incompatible with other new features as they are added.  See the
"Non-cone Problems" section below and the "Sparse Checkout" section of
linkgit:git-read-tree[1] for more details.
+
Use the `--[no-]sparse-index` option to use a sparse index (the
default is to not use it).  A sparse index reduces the size of the
index to be more closely aligned with your sparse-checkout
definition. This can have significant performance advantages for
commands such as `git status` or `git add`.  This feature is still
experimental. Some commands might be slower with a sparse index until
they are properly integrated with the feature.
+
**WARNING:** Using a sparse index requires modifying the index in a way
that is not completely understood by external tools. If you have trouble
with this compatibility, then run `git sparse-checkout init --no-sparse-index`
to rewrite your index to not be sparse. Older versions of Git will not
understand the sparse directory entries index extension and may fail to
interact with your repository until it is disabled.

'add'::
	Update the sparse-checkout file to include additional directories
	(in cone mode) or patterns (in non-cone mode).  By default, these
	directories or patterns are read from the command-line arguments,
	but they can be read from stdin using the `--stdin` option.

'reapply'::
	Reapply the sparsity pattern rules to paths in the working tree.
	Commands like merge or rebase can materialize paths to do their
	work (e.g. in order to show you a conflict), and other
	sparse-checkout commands might fail to sparsify an individual file
	(e.g. because it has unstaged changes or conflicts).  In such
	cases, it can make sense to run `git sparse-checkout reapply` later
	after cleaning up affected paths (e.g. resolving conflicts, undoing
	or committing changes, etc.).
+
The `reapply` command can also take `--[no-]cone` and `--[no-]sparse-index`
flags, with the same meaning as the flags from the `set` command, in order
to change which sparsity mode you are using without needing to also respecify
all sparsity paths.

'disable'::
	Disable the `core.sparseCheckout` config setting, and restore the
	working directory to include all files.

'init'::
	Deprecated command that behaves like `set` with no specified paths.
	May be removed in the future.
+
Historically, `set` did not handle all the necessary config settings,
which meant that both `init` and `set` had to be called.  Invoking
both meant the `init` step would first remove nearly all tracked files
(and in cone mode, ignored files too), then the `set` step would add
many of the tracked files (but not ignored files) back.  In addition
to the lost files, the performance and UI of this combination was
poor.
+
Also, historically, `init` would not actually initialize the
sparse-checkout file if it already existed.  This meant it was
possible to return to a sparse-checkout without remembering which
paths to pass to a subsequent 'set' or 'add' command.  However,
`--cone` and `--sparse-index` options would not be remembered across
the disable command, so the easy restore of calling a plain `init`
decreased in utility.

EXAMPLES
--------
`git sparse-checkout set MY/DIR1 SUB/DIR2`::

	Change to a sparse-checkout with all files (at any depth) under
	MY/DIR1/ and SUB/DIR2/ present in the working copy (plus all
	files immediately under MY/ and SUB/ and the toplevel
	directory).  If already in a sparse checkout, change which files
	are present in the working copy to this new selection.  Note
	that this command will also delete all ignored files in any
	directory that no longer has either tracked or
	non-ignored-untracked files present.

`git sparse-checkout disable`::

	Repopulate the working directory with all files, disabling sparse
	checkouts.

`git sparse-checkout add SOME/DIR/ECTORY`::

	Add all files under SOME/DIR/ECTORY/ (at any depth) to the
	sparse checkout, as well as all files immediately under
	SOME/DIR/ and immediately under SOME/.  Must already be in a
	sparse checkout before using this command.

`git sparse-checkout reapply`::

	It is possible for commands to update the working tree in a way
	that does not respect the selected sparsity directories, either
	because of special cases (such as hitting conflicts when
	merging/rebasing), or because some commands didn't fully support
	sparse checkouts (e.g. the old `recursive` merge backend had
	only limited support).  This command reapplies the existing
	sparse directory specifications to make the working directory
	match.

INTERNALS -- SPARSE CHECKOUT
----------------------------

"Sparse checkout" allows populating the working directory sparsely.  It
uses the skip-worktree bit (see linkgit: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, and the file is not present in the working tree,
then its absence is ignored. Git will avoid populating 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.

INTERNALS -- NON-CONE PROBLEMS
------------------------------

The `$GIT_DIR/info/sparse-checkout` file populated by the `set` and
`add` subcommands is defined to be a bunch of patterns (one per line)
using the same syntax as `.gitignore` files.  In cone mode, these
patterns are restricted to matching directories (and users only ever
need supply or see directory names), while in non-cone mode any
gitignore-style pattern is permitted.  Using the full gitignore-style
patterns in non-cone mode has a number of shortcomings:

  * Fundamentally, it makes various worktree-updating processes (pull,
    merge, rebase, switch, reset, checkout, etc.) require O(N*M) pattern
    matches, where N is the number of patterns and M is the number of
    paths in the index.  This scales poorly.

  * Avoiding the scaling issue means selecting paths via leading
    directory name or glob.  Passing globs on the command line is
    error-prone as users may forget to quote the glob, causing the
    shell to expand it into all matching files and pass them all
    individually along to sparse-checkout set/add.  This both
    exacerbates the scaling problem, and hardcodes the list of
    selected files to those which were present at the time the initial
    set/add subcommand was run (and thus ignoring other files matching
    the same glob which come into the working tree after switching
    branches or pulling down updates).

  * It uses "ignore"/"exclude" syntax for selecting what to "include",
    which periodically causes confusion.

  * It introduces inconsistencies in the Git command line, since other
    commands use pathspecs, but sparse-checkout (in non-cone mode) uses
    gitignore patterns.

  * It has edge cases where the "right" behavior is unclear.  Two examples:

    First, two users are in a subdirectory, and the first runs
       git sparse-checkout set '/toplevel-dir/*.c'
    while the second runs
       git sparse-checkout set relative-dir
    Should those arguments be transliterated into
       current/subdirectory/toplevel-dir/*.c
    and
       current/subdirectory/relative-dir
    before inserting into the sparse-checkout file?  The user who typed
    the first command is probably aware that arguments to set/add are
    supposed to be patterns in non-cone mode, and probably would not be
    happy with such a transliteration.  However, many gitignore-style
    patterns are just paths, which might be what the user who typed the
    second command was thinking, and they'd be upset if their argument
    wasn't transliterated.

    Second, what should bash-completion complete on for set/add commands
    for non-cone users?  If it suggests paths, is it exacerbating the
    problem above?  Also, if it suggests paths, what if the user has a
    file or directory that begins with either a '!' or '#' or has a '*',
    '\', '?', '[', or ']' in its name?  Completing on files or
    directories might give nasty surprises in such cases.

  * The excessive flexibility made other extensions essentially
    impractical.  `--sparse-index` may not have been feasible in
    non-cone mode, but even if it was, it would have been far more work
    to implement and may have been too slow in practice.  Some ideas for
    adding coupling between partial clones and sparse-checkouts are only
    practical with a more restricted set of paths.

For all these reasons, non-cone mode is deprecated.  Please switch to
using cone mode.

INTERNALS -- FULL PATTERN SET
-----------------------------

As noted above, the sparse-checkout file uses the same syntax as
`.gitignore` files; see linkgit:gitignore[5] for details.  Here, though,
the patterns are being used to select which files to include rather than
which files to exclude.

To complicate things a bit further, 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 select everything, and then to remove
the file `unwanted`:

----------------
/*
!unwanted
----------------


INTERNALS -- CONE PATTERN SET
-----------------------------

The full pattern set allows for arbitrary pattern matches and
complicated inclusion/exclusion rules. As noted above, this 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 used by default.

The accepted patterns in the cone pattern set are:

1. *Recursive:* All paths inside a directory are included.

2. *Parent:* All files immediately inside a directory are included.

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 set` with no directories
specified, 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. 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` (set by default or with an explicit
`--cone`), 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.


INTERNALS -- SUBMODULES
-----------------------

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.


SEE ALSO
--------

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

GIT
---
Part of the linkgit:git[1] suite