GIT-UPDATE-INDEX(1) Git Manual GIT-UPDATE-INDEX(1)

NAME

git-update-index - Register file contents in the working tree to the
index

SYNOPSIS

git update-index
[--add] [--remove | --force-remove] [--replace]
[--refresh] [-q] [--unmerged] [--ignore-missing]
[(--cacheinfo <mode>,<object>,<file>)...]
[--chmod=(+|-)x]
[--[no-]assume-unchanged]
[--[no-]skip-worktree]
[--[no-]ignore-skip-worktree-entries]
[--[no-]fsmonitor-valid]
[--ignore-submodules]
[--[no-]split-index]
[--[no-|test-|force-]untracked-cache]
[--[no-]fsmonitor]
[--really-refresh] [--unresolve] [--again | -g]
[--info-only] [--index-info]
[-z] [--stdin] [--index-version <n>]
[--show-index-version]
[--verbose]
[--] [<file>...]

DESCRIPTION

Modifies the index. Each file mentioned is updated into the index and
any unmerged or needs updating state is cleared.

See also git-add(1) for a more user-friendly way to do some of the
most common operations on the index.

The way git update-index handles files it is told about can be
modified using the various options:

OPTIONS

--add
If a specified file isn't in the index already then it's added.
Default behaviour is to ignore new files.

--remove
If a specified file is in the index but is missing then it's
removed. Default behavior is to ignore removed files.

--refresh
Looks at the current index and checks to see if merges or updates
are needed by checking stat() information.

-q
Quiet. If --refresh finds that the index needs an update, the
default behavior is to error out. This option makes git
update-index continue anyway.

--ignore-submodules
Do not try to update submodules. This option is only respected
when passed before --refresh.

--unmerged
If --refresh finds unmerged changes in the index, the default
behavior is to error out. This option makes git update-index
continue anyway.

--ignore-missing
Ignores missing files during a --refresh

--cacheinfo <mode>,<object>,<path>, --cacheinfo <mode> <object>
<path>
Directly insert the specified info into the index. For backward
compatibility, you can also give these three arguments as three
separate parameters, but new users are encouraged to use a
single-parameter form.

--index-info
Read index information from stdin.

--chmod=(+|-)x
Set the execute permissions on the updated files.

--[no-]assume-unchanged
When this flag is specified, the object names recorded for the
paths are not updated. Instead, this option sets/unsets the
"assume unchanged" bit for the paths. When the "assume unchanged"
bit is on, the user promises not to change the file and allows
Git to assume that the working tree file matches what is recorded
in the index. If you want to change the working tree file, you
need to unset the bit to tell Git. This is sometimes helpful when
working with a big project on a filesystem that has a very slow
lstat(2) system call (e.g. cifs).

Git will fail (gracefully) in case it needs to modify this file
in the index e.g. when merging in a commit; thus, in case the
assumed-untracked file is changed upstream, you will need to
handle the situation manually.

--really-refresh
Like --refresh, but checks stat information unconditionally,
without regard to the "assume unchanged" setting.

--[no-]skip-worktree
When one of these flags is specified, the object names recorded
for the paths are not updated. Instead, these options set and
unset the "skip-worktree" bit for the paths. See section
"Skip-worktree bit" below for more information.

--[no-]ignore-skip-worktree-entries
Do not remove skip-worktree (AKA "index-only") entries even when
the --remove option was specified.

--[no-]fsmonitor-valid
When one of these flags is specified, the object names recorded
for the paths are not updated. Instead, these options set and
unset the "fsmonitor valid" bit for the paths. See section "File
System Monitor" below for more information.

-g, --again
Runs git update-index itself on the paths whose index entries are
different from those of the HEAD commit.

--unresolve
Restores the unmerged or needs updating state of a file during a
merge if it was cleared by accident.

--info-only
Do not create objects in the object database for all <file>
arguments that follow this flag; just insert their object IDs
into the index.

--force-remove
Remove the file from the index even when the working directory
still has such a file. (Implies --remove.)

--replace
By default, when a file path exists in the index, git
update-index refuses an attempt to add path/file. Similarly if a
file path/file exists, a file path cannot be added. With
--replace flag, existing entries that conflict with the entry
being added are automatically removed with warning messages.

--stdin
Instead of taking a list of paths from the command line, read a
list of paths from the standard input. Paths are separated by LF
(i.e. one path per line) by default.

--verbose
Report what is being added and removed from the index.

--index-version <n>
Write the resulting index out in the named on-disk format
version. Supported versions are 2, 3, and 4. The current default
version is 2 or 3, depending on whether extra features are used,
such as git add -N. With --verbose, also report the version the
index file uses before and after this command.

Version 4 performs a simple pathname compression that reduces
index size by 30%-50% on large repositories, which results in
faster load time. Git supports it since version 1.8.0, released
in October 2012, and support for it was added to libgit2 in 2016
and to JGit in 2020. Older versions of this manual page called it
"relatively young", but it should be considered mature technology
these days.

--show-index-version
Report the index format version used by the on-disk index file.
See --index-version above.

-z
Only meaningful with --stdin or --index-info; paths are separated
with NUL character instead of LF.

--split-index, --no-split-index
Enable or disable split index mode. If split-index mode is
already enabled and --split-index is given again, all changes in
$GIT_DIR/index are pushed back to the shared index file.

These options take effect whatever the value of the
core.splitIndex configuration variable (see git-config(1)). But a
warning is emitted when the change goes against the configured
value, as the configured value will take effect next time the
index is read and this will remove the intended effect of the
option.

--untracked-cache, --no-untracked-cache
Enable or disable untracked cache feature. Please use
--test-untracked-cache before enabling it.

These options take effect whatever the value of the
core.untrackedCache configuration variable (see git-config(1)).
But a warning is emitted when the change goes against the
configured value, as the configured value will take effect next
time the index is read and this will remove the intended effect
of the option.

--test-untracked-cache
Only perform tests on the working directory to make sure
untracked cache can be used. You have to manually enable
untracked cache using --untracked-cache or
--force-untracked-cache or the core.untrackedCache configuration
variable afterwards if you really want to use it. If a test fails
the exit code is 1 and a message explains what is not working as
needed, otherwise the exit code is 0 and OK is printed.

--force-untracked-cache
Same as --untracked-cache. Provided for backwards compatibility
with older versions of Git where --untracked-cache used to imply
--test-untracked-cache but this option would enable the extension
unconditionally.

--fsmonitor, --no-fsmonitor
Enable or disable files system monitor feature. These options
take effect whatever the value of the core.fsmonitor
configuration variable (see git-config(1)). But a warning is
emitted when the change goes against the configured value, as the
configured value will take effect next time the index is read and
this will remove the intended effect of the option.

--
Do not interpret any more arguments as options.

<file>
Files to act on. Note that files beginning with . are discarded.
This includes ./file and dir/./file. If you don't want this, then
use cleaner names. The same applies to directories ending / and
paths with //

USING --REFRESH
--refresh does not calculate a new sha1 file or bring the index up to
date for mode/content changes. But what it does do is to "re-match"
the stat information of a file with the index, so that you can
refresh the index for a file that hasn't been changed but where the
stat entry is out of date.

For example, you'd want to do this after doing a git read-tree, to
link up the stat index details with the proper files.

USING --CACHEINFO OR --INFO-ONLY
--cacheinfo is used to register a file that is not in the current
working directory. This is useful for minimum-checkout merging.

To pretend you have a file at path with mode and sha1, say:

$ git update-index --add --cacheinfo <mode>,<sha1>,<path>

--info-only is used to register files without placing them in the
object database. This is useful for status-only repositories.

Both --cacheinfo and --info-only behave similarly: the index is
updated but the object database isn't. --cacheinfo is useful when the
object is in the database but the file isn't available locally.
--info-only is useful when the file is available, but you do not wish
to update the object database.

USING --INDEX-INFO
--index-info is a more powerful mechanism that lets you feed multiple
entry definitions from the standard input, and designed specifically
for scripts. It can take inputs of three formats:

1. mode SP type SP sha1 TAB path

This format is to stuff git ls-tree output into the index.

2. mode SP sha1 SP stage TAB path

This format is to put higher order stages into the index file and
matches git ls-files --stage output.

3. mode SP sha1 TAB path

This format is no longer produced by any Git command, but is and
will continue to be supported by update-index --index-info.

To place a higher stage entry to the index, the path should first be
removed by feeding a mode=0 entry for the path, and then feeding
necessary input lines in the third format.

For example, starting with this index:

$ git ls-files -s
100644 8a1218a1024a212bb3db30becd860315f9f3ac52 0 frotz

you can feed the following input to --index-info:

$ git update-index --index-info
0 0000000000000000000000000000000000000000 frotz
100644 8a1218a1024a212bb3db30becd860315f9f3ac52 1 frotz
100755 8a1218a1024a212bb3db30becd860315f9f3ac52 2 frotz

The first line of the input feeds 0 as the mode to remove the path;
the SHA-1 does not matter as long as it is well formatted. Then the
second and third line feeds stage 1 and stage 2 entries for that
path. After the above, we would end up with this:

$ git ls-files -s
100644 8a1218a1024a212bb3db30becd860315f9f3ac52 1 frotz
100755 8a1218a1024a212bb3db30becd860315f9f3ac52 2 frotz

USING "ASSUME UNCHANGED" BIT
Many operations in Git depend on your filesystem to have an efficient
lstat(2) implementation, so that st_mtime information for working
tree files can be cheaply checked to see if the file contents have
changed from the version recorded in the index file. Unfortunately,
some filesystems have inefficient lstat(2). If your filesystem is one
of them, you can set "assume unchanged" bit to paths you have not
changed to cause Git not to do this check. Note that setting this bit
on a path does not mean Git will check the contents of the file to
see if it has changed -- it makes Git to omit any checking and assume
it has not changed. When you make changes to working tree files, you
have to explicitly tell Git about it by dropping "assume unchanged"
bit, either before or after you modify them.

In order to set "assume unchanged" bit, use --assume-unchanged
option. To unset, use --no-assume-unchanged. To see which files have
the "assume unchanged" bit set, use git ls-files -v (see git-ls-
files(1)).

The command looks at core.ignorestat configuration variable. When
this is true, paths updated with git update-index paths... and paths
updated with other Git commands that update both index and working
tree (e.g. git apply --index, git checkout-index -u, and git
read-tree -u) are automatically marked as "assume unchanged". Note
that "assume unchanged" bit is not set if git update-index --refresh
finds the working tree file matches the index (use git update-index
--really-refresh if you want to mark them as "assume unchanged").

Sometimes users confuse the assume-unchanged bit with the
skip-worktree bit. See the final paragraph in the "Skip-worktree bit"
section below for an explanation of the differences.

EXAMPLES

To update and refresh only the files already checked out:

$ git checkout-index -n -f -a && git update-index --ignore-missing --refresh

On an inefficient filesystem with core.ignorestat set

$ git update-index --really-refresh (1)
$ git update-index --no-assume-unchanged foo.c (2)
$ git diff --name-only (3)
$ edit foo.c
$ git diff --name-only (4)
M foo.c
$ git update-index foo.c (5)
$ git diff --name-only (6)
$ edit foo.c
$ git diff --name-only (7)
$ git update-index --no-assume-unchanged foo.c (8)
$ git diff --name-only (9)
M foo.c

1. forces lstat(2) to set
"assume unchanged" bits
for paths that match
index.
2. mark the path to be
edited.
3. this does lstat(2) and
finds index matches the
path.
4. this does lstat(2) and
finds index does not
match the path.
5. registering the new
version to index sets
"assume unchanged" bit.
6. and it is assumed
unchanged.
7. even after you edit it.
8. you can tell about the
change after the fact.
9. now it checks with
lstat(2) and finds it has
been changed.

SKIP-WORKTREE BIT
Skip-worktree bit can be defined in one (long) sentence: Tell git to
avoid writing the file to the working directory when reasonably
possible, and treat the file as unchanged when it is not present in
the working directory.

Note that not all git commands will pay attention to this bit, and
some only partially support it.

The update-index flags and the read-tree capabilities relating to the
skip-worktree bit predated the introduction of the git-sparse-
checkout(1) command, which provides a much easier way to configure
and handle the skip-worktree bits. If you want to reduce your working
tree to only deal with a subset of the files in the repository, we
strongly encourage the use of git-sparse-checkout(1) in preference to
the low-level update-index and read-tree primitives.

The primary purpose of the skip-worktree bit is to enable sparse
checkouts, i.e. to have working directories with only a subset of
paths present. When the skip-worktree bit is set, Git commands (such
as switch, pull, merge) will avoid writing these files. However,
these commands will sometimes write these files anyway in important
cases such as conflicts during a merge or rebase. Git commands will
also avoid treating the lack of such files as an intentional
deletion; for example git add -u will not stage a deletion for these
files and git commit -a will not make a commit deleting them either.

Although this bit looks similar to assume-unchanged bit, its goal is
different. The assume-unchanged bit is for leaving the file in the
working tree but having Git omit checking it for changes and
presuming that the file has not been changed (though if it can
determine without stat'ing the file that it has changed, it is free
to record the changes). skip-worktree tells Git to ignore the absence
of the file, avoid updating it when possible with commands that
normally update much of the working directory (e.g. checkout, switch,
pull, etc.), and not have its absence be recorded in commits. Note
that in sparse checkouts (setup by git sparse-checkout or by
configuring core.sparseCheckout to true), if a file is marked as
skip-worktree in the index but is found in the working tree, Git will
clear the skip-worktree bit for that file.

SPLIT INDEX

This mode is designed for repositories with very large indexes, and
aims at reducing the time it takes to repeatedly write these indexes.

In this mode, the index is split into two files, $GIT_DIR/index and
$GIT_DIR/sharedindex.<SHA-1>. Changes are accumulated in
$GIT_DIR/index, the split index, while the shared index file contains
all index entries and stays unchanged.

All changes in the split index are pushed back to the shared index
file when the number of entries in the split index reaches a level
specified by the splitIndex.maxPercentChange config variable (see
git-config(1)).

Each time a new shared index file is created, the old shared index
files are deleted if their modification time is older than what is
specified by the splitIndex.sharedIndexExpire config variable (see
git-config(1)).

To avoid deleting a shared index file that is still used, its
modification time is updated to the current time every time a new
split index based on the shared index file is either created or read
from.

UNTRACKED CACHE

This cache is meant to speed up commands that involve determining
untracked files such as git status.

This feature works by recording the mtime of the working tree
directories and then omitting reading directories and stat calls
against files in those directories whose mtime hasn't changed. For
this to work the underlying operating system and file system must
change the st_mtime field of directories if files in the directory
are added, modified or deleted.

You can test whether the filesystem supports that with the
--test-untracked-cache option. The --untracked-cache option used to
implicitly perform that test in older versions of Git, but that's no
longer the case.

If you want to enable (or disable) this feature, it is easier to use
the core.untrackedCache configuration variable (see git-config(1))
than using the --untracked-cache option to git update-index in each
repository, especially if you want to do so across all repositories
you use, because you can set the configuration variable to true (or
false) in your $HOME/.gitconfig just once and have it affect all
repositories you touch.

When the core.untrackedCache configuration variable is changed, the
untracked cache is added to or removed from the index the next time a
command reads the index; while when --[no-|force-]untracked-cache are
used, the untracked cache is immediately added to or removed from the
index.

Before 2.17, the untracked cache had a bug where replacing a
directory with a symlink to another directory could cause it to
incorrectly show files tracked by git as untracked. See the "status:
add a failing test showing a core.untrackedCache bug" commit to
git.git. A workaround for that is (and this might work for other
undiscovered bugs in the future):

$ git -c core.untrackedCache=false status

This bug has also been shown to affect non-symlink cases of replacing
a directory with a file when it comes to the internal structures of
the untracked cache, but no case has been reported where this
resulted in wrong "git status" output.

There are also cases where existing indexes written by git versions
before 2.17 will reference directories that don't exist anymore,
potentially causing many "could not open directory" warnings to be
printed on "git status". These are new warnings for existing issues
that were previously silently discarded.

As with the bug described above the solution is to one-off do a "git
status" run with core.untrackedCache=false to flush out the leftover
bad data.

FILE SYSTEM MONITOR

This feature is intended to speed up git operations for repos that
have large working directories.

It enables git to work together with a file system monitor (see git-
fsmonitor--daemon(1) and the "fsmonitor-watchman" section of
githooks(5)) that can inform it as to what files have been modified.
This enables git to avoid having to lstat() every file to find
modified files.

When used in conjunction with the untracked cache, it can further
improve performance by avoiding the cost of scanning the entire
working directory looking for new files.

If you want to enable (or disable) this feature, it is easier to use
the core.fsmonitor configuration variable (see git-config(1)) than
using the --fsmonitor option to git update-index in each repository,
especially if you want to do so across all repositories you use,
because you can set the configuration variable in your
$HOME/.gitconfig just once and have it affect all repositories you
touch.

When the core.fsmonitor configuration variable is changed, the file
system monitor is added to or removed from the index the next time a
command reads the index. When --[no-]fsmonitor are used, the file
system monitor is immediately added to or removed from the index.

CONFIGURATION

The command honors core.filemode configuration variable. If your
repository is on a filesystem whose executable bits are unreliable,
this should be set to false (see git-config(1)). This causes the
command to ignore differences in file modes recorded in the index and
the file mode on the filesystem if they differ only on executable
bit. On such an unfortunate filesystem, you may need to use git
update-index --chmod=.

Quite similarly, if core.symlinks configuration variable is set to
false (see git-config(1)), symbolic links are checked out as plain
files, and this command does not modify a recorded file mode from
symbolic link to regular file.

The command looks at core.ignorestat configuration variable. See
Using "assume unchanged" bit section above.

The command also looks at core.trustctime configuration variable. It
can be useful when the inode change time is regularly modified by
something outside Git (file system crawlers and backup systems use
ctime for marking files processed) (see git-config(1)).

The untracked cache extension can be enabled by the
core.untrackedCache configuration variable (see git-config(1)).

NOTES

Users often try to use the assume-unchanged and skip-worktree bits to
tell Git to ignore changes to files that are tracked. This does not
work as expected, since Git may still check working tree files
against the index when performing certain operations. In general, Git
does not provide a way to ignore changes to tracked files, so
alternate solutions are recommended.

For example, if the file you want to change is some sort of config
file, the repository can include a sample config file that can then
be copied into the ignored name and modified. The repository can even
include a script to treat the sample file as a template, modifying
and copying it automatically.

SEE ALSO

git-config(1), git-add(1), git-ls-files(1)

GIT

Part of the git(1) suite

Git 2.48.1 2025-01-13 GIT-UPDATE-INDEX(1)