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-]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>...]
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>, --cacheinfo <mode> <object> <path>
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.
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.
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.
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.
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.
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.
This format is to stuff git ls-tree output into the index.
This format is to put higher order stages into the index file and matches git ls-files --stage output.
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
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").
$ 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.
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.
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 everytime a new split index based on the shared index file is either created or read from.
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.
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.
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)).