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GIT-INDEX-PACK(1)                            Git Manual                            GIT-INDEX-PACK(1)



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                                   02/26/2026                            GIT-INDEX-PACK(1)