要約

When you clone a Git repository, it typically comes in a packed format, which allows for efficient data transfer and compression. Packed files are stored in the .git/objects/pack on Git Working directory and contain compressed Git objects. While this format is great for efficiency, it makes inspecting individual Git objects challenging.

To manually inspect these objects, you can unpack the .pack file, which will allow you to browse the Git pack file more easily. This article outlines the steps to unpack a Git pack file, though it is generally not recommended unless necessary for inspection or extraction of a specific Git object, as unpacking can increase storage usage.

環境

Applies for Git working Copy and Git Server Side Bare Repo

ソリューション

Steps to Unpack a Git Pack File:

• Backup

  Create a backup of your local Git working copy or Git Server Side repository before you start making any changes to it.

  Then run all the steps below on the backed-up copy and avoid running them on the original directory.

• Change the directory and switch to the backed-up Git repo copy.

  
  

  cd backedup_repo

• Move the `.pack` file out of the `.git/objects/pack` directory if working on a Git working copy.
  • In case this is done on the Bitbucket server-side bare repository, the `.pack` files will be located under:  
    `$BITBUCKET_SHARED/data/repositories/<repo_dir_id>/objects/pack/`.

• ##### Git Working Copy #######
  mv .git/objects/pack/pack-*.pack .
  
  ##### Git Bare Repo Server Side #######
  mv objects/pack/pack-*.pack .

• In case you are looking to unpack the pack file to extract only a specific Git object, you can determine where the specific Git object lies by running the command below.

• git verify-pack -v <path_to_pack_file_name.pack> | grep 188243b8c124794c310a6d9f3be9ecaceac05930 # grep for the Git Object  
  ##### Output ######
  188243b8c124794c310a6d9f3be9ecaceac05930 commit 418 252 1447

• Once you have identified the pack file that needs to be unpacked, you can execute the command below. This command will unpack the pack file into loose objects.

• git unpack-objects < packfile_that_has_the_object.pack

• The above process should unpack the objects from the pack file and place them under the corresponding folders for the Git local working copy.

  • The loose objects will be located in the `.git/objects/` directory, and the specific commit object `188243b8c124794c310a6d9f3be9ecaceac05930` will be found at the path `.git/objects/18/8243b8c124794c310a6d9f3be9ecaceac05930`. 

• If this unpack command is executed on the Git bare repository on the Bitbucket server-side backup copy, then the objects will be located in the `/objects` directory. In this case, the specific commit object `188243b8c124794c310a6d9f3be9ecaceac05930` will be found at the path `objects/18/8243b8c124794c310a6d9f3be9ecaceac05930`.

• After successful unpacking, you can safely remove the .pack file that you unpacked by deleting it.

• 情報

  The above approach is mostly used to extract a specific Git object from a packed file. This situation might occur if some of the packed objects are missing due to corruption on the Production Bitbucket server side. The solution is to copy the correct Git objects back to the server, and for that, they must be extracted from any old server backup or from any Git working copy. This is when unpacking and extracting Git objects becomes useful.