unpack-trees: failure to set SKIP_WORKTREE bits always just a warning

[thirdparty/git.git] / Documentation / git-sparse-checkout.txt

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

NAME
----
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.


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


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

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.


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

'init'::
	Enable the `core.sparseCheckout` setting. If the
	sparse-checkout file does not exist, then populate it with
	patterns that match every file in the root directory and
	no other directories, then will remove all directories tracked
	by Git. Add patterns to the sparse-checkout file to
	repopulate the working directory.
+
To avoid interfering with other worktrees, it first enables the
`extensions.worktreeConfig` setting and makes sure to set the
`core.sparseCheckout` setting in the worktree-specific config file.
+
When `--cone` is provided, the `core.sparseCheckoutCone` setting is
also set, allowing for better performance with a limited set of
patterns (see 'CONE PATTERN SET' below).

'set'::
	Write a set of patterns to the sparse-checkout file, as given as
	a list of arguments following the 'set' subcommand. Update the
	working directory to match the new patterns. Enable the
	core.sparseCheckout config setting if it is not already enabled.
+
When the `--stdin` option is provided, the patterns are read from
standard in as a newline-delimited list instead of from the arguments.
+
When `core.sparseCheckoutCone` is enabled, the input list is considered a
list of directories instead of sparse-checkout patterns. The command writes
patterns to the sparse-checkout file to include all files contained in those
directories (recursively) as well as files that are siblings of ancestor
directories. The input format matches the output of `git ls-tree --name-only`.
This includes interpreting pathnames that begin with a double quote (") as
C-style quoted strings.

'add'::
	Update the sparse-checkout file to include additional patterns.
	By default, these patterns are read from the command-line arguments,
	but they can be read from stdin using the `--stdin` option. When
	`core.sparseCheckoutCone` is enabled, the given patterns are interpreted
	as directory names as in the 'set' subcommand.

'disable'::
	Disable the `core.sparseCheckout` config setting, and restore the
	working directory to include all files. Leaves the sparse-checkout
	file intact so a later 'git sparse-checkout init' command may
	return the working directory to the same state.

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, 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.


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

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
----------------


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

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:

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 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.


SUBMODULES
----------

If your repository contains one or more submodules, then those submodules will
appear based on which you initialized with the `git submodule` command. If
your sparse-checkout patterns exclude an initialized submodule, then that
submodule will still appear in your working directory.


SEE ALSO
--------

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

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