SYNOPSIS
--------
+[verse]
'git-update-index'
[--add] [--remove | --force-remove] [--replace]
[--refresh [-q] [--unmerged] [--ignore-missing]]
[--cacheinfo <mode> <object> <file>]\*
[--chmod=(+|-)x]
+ [--assume-unchanged | --no-assume-unchanged]
+ [--really-refresh]
[--info-only] [--index-info]
[-z] [--stdin]
[--verbose]
--chmod=(+|-)x::
Set the execute permissions on the updated files.
+--assume-unchanged, --no-assume-unchanged::
+ When these flags are specified, the object name recorded
+ for the paths are not updated. Instead, these options
+ sets and unsets the "assume unchanged" bit for the
+ paths. When the "assume unchanged" bit is on, git stops
+ checking the working tree files for possible
+ modifications, so you need to manually unset the bit to
+ tell git when you change the working tree file. This is
+ sometimes helpful when working with a big project on a
+ filesystem that has very slow lstat(2) system call
+ (e.g. cifs).
+
--info-only::
Do not create objects in the object database for all
<file> arguments that follow this flag; just insert
------------
+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`.
+
+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").
+
+
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.
+------------
+
Configuration
-------------
executable bit. On such an unfortunate filesystem, you may
need to use `git-update-index --chmod=`.
+The command looks at `core.ignorestat` configuration variable. See
+'Using "assume unchanged" bit' section above.
+
See Also
--------