git-update-index






git‐update‐index − Register file contents in the working
tree to the index



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>]
             [−−verbose]
             [−−] [<file>...]




Modifies the index or directory cache. 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:



     −−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
     file.

     −−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









                             ‐2‐


     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 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 name









                             ‐3‐


     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 name
     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 from 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 list of paths from the command line,
     read 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 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.









                             ‐4‐


     Version 4 performs a simple pathname compression that
     reduces index size by 30%−50% on large repositories,
     which results in faster load time. Version 4 is
     relatively young (first released in 1.8.0 in October
     2012). Other Git implementations such as JGit and
     libgit2 may not support it yet.

     −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









                             ‐5‐


     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 //



−−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.



−−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.



−−index−info is a more powerful mechanism that lets you feed
multiple entry definitions from the standard input, and









                             ‐6‐


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




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









                             ‐7‐


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").



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.









                             ‐8‐


     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 can be defined in one (long) sentence:
When reading an entry, if it is marked as skip−worktree,
then Git pretends its working directory version is up to
date and read the index version instead.

To elaborate, "reading" means checking for file existence,
reading file attributes or file content. The working
directory version may be present or absent. If present, its
content may match against the index version or not. Writing
is not affected by this bit, content safety is still first
priority. Note that Git can update working directory file,
that is marked skip−worktree, if it is safe to do so (i.e.
working directory version matches index version)

Although this bit looks similar to assume−unchanged bit, its
goal is different from assume−unchanged bit’s. Skip−worktree
also takes precedence over assume−unchanged bit when both
are set.



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)).









                             ‐9‐


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.



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.









                            ‐10‐


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.



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 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.



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.









                            ‐11‐


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)).



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.



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



Part of the git(1) suite