git update-index [--add] [--remove | --force-remove] [--replace] [--refresh] [-q] [--unmerged] [--ignore-missing] [(--cacheinfo <mode> <object> <file>)...] [--chmod=(+|-)x] [--assume-unchanged | --no-assume-unchanged] [--skip-worktree | --no-skip-worktree] [--ignore-submodules] [--really-refresh] [--unresolve] [--again | -g] [--info-only] [--index-info] [-z] [--stdin] [--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:
--cacheinfo <mode> <object> <path>
This option can be also used as a coarse file-level mechanism to ignore uncommitted changes in tracked files (akin to what .gitignore does for untracked files). 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.
--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file with the index, so that you can refresh the index for a file that hasn't been changed but where the stat entry is out of date.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 with mode and sha1 at path, say:
$ git update-index --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 designed specifically for scripts. It can take inputs of three formats:
The first format is what "git-apply --index-info" reports, and used to reconstruct a partial tree that is used for phony merge base tree when falling back on 3-way merge.
The second format is to stuff git ls-tree output into the index file.
This format is to put higher order stages into the index file and matches git ls-files --stage output.
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 SHA1 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 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").
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 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.
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)).
Written by Linus Torvalds <m[blue]firstname.lastname@example.org>
Documentation by David Greaves, Junio C Hamano and the git-list <m[blue]email@example.com>.
Part of the git(1) suite