Git Update Index Command Options and Usage

'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: . mode SP type SP sha1 TAB path + This format is to stuff `git ls-tree` output into the index. . 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. . 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 linkgit: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

The git update-index command provides options like --cacheinfo, --info-only, and --index-info to register files and update the index without modifying the object database, as well as options to set the 'assume unchanged' bit to omit file checking and assume files have not changed, with various use cases and examples provided.