NAME

       git-index-pack - Build pack index file for an existing packed archive

SYNOPSIS

       git index-pack [-v] [-o <index-file>] [--[no-]rev-index] <pack-file>
       git index-pack --stdin [--fix-thin] [--keep] [-v] [-o <index-file>]
                         [--[no-]rev-index] [<pack-file>]

DESCRIPTION

       Reads a packed archive (.pack) from the specified file, and builds a pack index file (.idx) for it.
       Optionally writes a reverse-index (.rev) for the specified pack. The packed archive together with the
       pack index can then be placed in the objects/pack/ directory of a Git repository.

OPTIONS

       -v
           Be verbose about what is going on, including progress status.

       -o <index-file>
           Write the generated pack index into the specified file. Without this option the name of pack index
           file is constructed from the name of packed archive file by replacing .pack with .idx (and the
           program fails if the name of packed archive does not end with .pack).

       --[no-]rev-index
           When this flag is provided, generate a reverse index (a .rev file) corresponding to the given pack.
           If --verify is given, ensure that the existing reverse index is correct. Takes precedence over
           pack.writeReverseIndex.

       --stdin
           When this flag is provided, the pack is read from stdin instead and a copy is then written to
           <pack-file>. If <pack-file> is not specified, the pack is written to objects/pack/ directory of the
           current Git repository with a default name determined from the pack content. If <pack-file> is not
           specified consider using --keep to prevent a race condition between this process and git repack.

       --fix-thin
           Fix a "thin" pack produced by git pack-objects --thin (see git-pack-objects(1) for details) by adding
           the excluded objects the deltified objects are based on to the pack. This option only makes sense in
           conjunction with --stdin.

       --keep
           Before moving the index into its final destination create an empty .keep file for the associated pack
           file. This option is usually necessary with --stdin to prevent a simultaneous git repack process from
           deleting the newly constructed pack and index before refs can be updated to use objects contained in
           the pack.

       --keep=<msg>
           Like --keep create a .keep file before moving the index into its final destination, but rather than
           creating an empty file place <msg> followed by an LF into the .keep file. The <msg> message can later
           be searched for within all .keep files to locate any which have outlived their usefulness.

       --index-version=<version>[,<offset>]
           This is intended to be used by the test suite only. It allows to force the version for the generated
           pack index, and to force 64-bit index entries on objects located above the given offset.

       --strict
           Die, if the pack contains broken objects or links.

       --progress-title
           For internal use only.

           Set the title of the progress bar. The title is "Receiving objects" by default and "Indexing objects"
           when --stdin is specified.

       --check-self-contained-and-connected
           Die if the pack contains broken links. For internal use only.

       --fsck-objects
           For internal use only.

           Die if the pack contains broken objects. If the pack contains a tree pointing to a .gitmodules blob
           that does not exist, prints the hash of that blob (for the caller to check) after the hash that goes
           into the name of the pack/idx file (see "Notes").

       --threads=<n>
           Specifies the number of threads to spawn when resolving deltas. This requires that index-pack be
           compiled with pthreads otherwise this option is ignored with a warning. This is meant to reduce
           packing time on multiprocessor machines. The required amount of memory for the delta search window is
           however multiplied by the number of threads. Specifying 0 will cause Git to auto-detect the number of
           CPU’s and use maximum 3 threads.

       --max-input-size=<size>
           Die, if the pack is larger than <size>.

       --object-format=<hash-algorithm>
           Specify the given object format (hash algorithm) for the pack. The valid values are sha1 and (if
           enabled) sha256. The default is the algorithm for the current repository (set by
           extensions.objectFormat), or sha1 if no value is set or outside a repository.

           This option cannot be used with --stdin.

           THIS OPTION IS EXPERIMENTAL! SHA-256 support is experimental and still in an early stage. A SHA-256
           repository will in general not be able to share work with "regular" SHA-1 repositories. It should be
           assumed that, e.g., Git internal file formats in relation to SHA-256 repositories may change in
           backwards-incompatible ways. Only use --object-format=sha256 for testing purposes.

NOTES

       Once the index has been created, the hash that goes into the name of the pack/idx file is printed to
       stdout. If --stdin was also used then this is prefixed by either "pack\t", or "keep\t" if a new .keep
       file was successfully created. This is useful to remove a .keep file used as a lock to prevent the race
       with git repack mentioned above.

GIT

       Part of the git(1) suite

Git 2.34.1                                         07/09/2025                                  GIT-INDEX-PACK(1)