Exporting a Git Repository Tree: Techniques and Tools

Introduction

Git is a powerful version control system widely used for managing source code. One common requirement when working with Git repositories is to export a snapshot of the repository’s file tree without including the .git directory or any other metadata files like .gitignore. This tutorial explores various methods to achieve this, effectively mimicking an "svn export" in Git.

Understanding the Requirement

When you want to share your codebase without exposing version control information or when preparing a deployment package, you need a clean copy of the repository’s contents. The challenge lies in exporting only the files and directories within the specified branch while excluding any hidden .git directory or other metadata files that are not part of the source tree.

Methods to Export a Git Tree

Method 1: Using git archive

The git archive command is one of the most straightforward ways to export a repository tree. It allows you to create an archive (such as tarball or zip) from any branch, tag, or commit. This method ensures that all files are included, but it requires attention to exclude unwanted metadata like .gitignore.

Basic Usage

To archive the master branch and extract it into a directory:

mkdir /somewhere/else
git archive master | tar -x -C /somewhere/else

For creating compressed archives:

# Creating a bzip2-compressed archive
git archive master | bzip2 > source-tree.tar.bz2

# Creating a ZIP archive
git archive --format zip --output /full/path/to/zipfile.zip master

Excluding Metadata Files

To prevent .gitignore and similar files from being included:

1. Create or update a .gitattributes file in your repository.
2. Add the export-ignore attribute to any files you wish to exclude.

Example:

.gitignore export-ignore
.gitattributes export-ignore

Commit these changes before running git archive.

Method 2: Using git checkout-index

The git checkout-index command can be utilized for exporting a tree by writing the contents of the index (staging area) to a specified directory. This method is particularly useful when you want direct control over which files are included in the export.

Basic Usage

git checkout-index -a -f --prefix=/destination/path/

• -a: Ensures all files tracked by Git are checked out.
• -f: Forces overwriting of existing files at the destination.
• --prefix: Specifies a prefix for the exported directory path.

Method 3: Using Third-party Tools

Some third-party scripts and tools mimic an "svn export" style operation. For instance, the script git-export clones the repository into a temporary location, then uses rsync to transfer files excluding the .git directory. While effective, this approach involves additional dependencies.

Method 4: Exporting from Remote Repositories

The git archive command can also be used with remote repositories:

git archive --format=tar --remote=ssh://remote_server/remote_repository master | tar -xf -

To export specific paths within a repository, append the path arguments at the end.

Special Case: Using SVN Export on GitHub

For repositories hosted on GitHub that support SVN, you can directly use svn export:

svn export https://github.com/username/repo-name/trunk/

This approach is convenient when working with branches or tags as it uses standard SVN commands to access Git-based repositories.

Conclusion

Exporting a Git repository tree without the .git directory can be achieved through several methods, each with its own advantages. The git archive command offers simplicity and flexibility for most cases, while git checkout-index provides precise control over the export process. Understanding these tools allows developers to share or deploy codebases effectively, maintaining a clean separation from version control metadata.