Git — A Video Map Guide

Torvalds started developing Git in April 2005 after the free license for BitKeeper, the proprietary source-control management (SCM) system used for Linux kernel development since 2002, was revoked for Linux. The copyright holder of BitKeeper, Larry McVoy, claimed that Andrew Tridgell had created SourcePuller by reverse engineering the BitKeeper protocols. The same incident also spurred the creation of Mercurial, another version-control system. Torvalds wanted a distributed system that he could use like BitKeeper, but none of the available free systems met his needs. He cited an example of a source-control management system needing 30 seconds to apply a patch and update all associated metadata, and noted that this would not scale to the needs of Linux kernel development, where synchronizing with fellow maintainers could require 250 such actions at once. For his design criterion, he specified that patching should take no more than three seconds, and added three more goals: Take the Concurrent Versions System (CVS) as an example of what not to do; if in doubt, make the exact opposite decision. Support a distributed, BitKeeper-like workflow. Include very strong safeguards against corruption, either accidental or malicious. These criteria eliminated every version-control system in use at the time, so immediately after the 2.6.12-rc2 Linux kernel development release, Torvalds set out to write his own. The development of Git began on 3 April 2005. Torvalds announced the project on 6 April and became self-hosting the next day. The first merge of multiple branches took place on 18 April. Torvalds achieved his performance goals; on 29 April, the nascent Git was benchmarked recording patches to the Linux kernel tree at a rate of 6.7 patches per second. On 16 June, Git managed the kernel 2.6.12 rel

Design Git's design is a synthesis of Torvalds's experience with Linux in maintaining a large distributed development project, along with his intimate knowledge of file-system performance gained from the same project and the urgent need to produce a working system in short order. These influences led to the following implementation choices: Strong support for non-linear development Git supports rapid branching and merging, and includes specific tools for visualizing and navigating a non-linear development history. In Git, a core assumption is that a change will be merged more often than it is written, as it is passed around to various reviewers. In Git, branches are very lightweight: a branch is only a reference to one commit. Distributed development Like Darcs, BitKeeper, Mercurial, Bazaar, and Monotone, Git gives each developer a local copy of the full development history, and changes are copied from one such repository to another. These changes are imported as added development branches and can be merged in the same way as a locally developed branch. Compatibility with existing systems and protocols Repositories can be published via Hypertext Transfer Protocol Secure (HTTPS), Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), or a Git protocol over either a plain socket or Secure Shell (ssh). Git also has a CVS server emulation, which enables the use of existing CVS clients and IDE plugins to access Git repositories. Subversion repositories can be used directly with git-svn. Efficient handling of large projects Torvalds has described Git as being very fast and scalable, and performance tests done by Mozilla showed that it was an order of magnitude faster diffing large repositories than Mercurial and GNU Bazaar; fetching version history from a locally stored repository can be one hundred times faster than fetching it from the remote server.&#

gitg is a graphical front-end using GTK+. Git (the main implementation in C) is primarily developed on Linux, although it also supports most major operating systems, including the BSDs (DragonFly BSD, FreeBSD, NetBSD, and OpenBSD), Solaris, macOS, and Windows. The first Windows port of Git was primarily a Linux-emulation framework that hosts the Linux version. Installing Git under Windows creates a similarly named Program Files directory containing the Mingw-w64 port of the GNU Compiler Collection, Perl 5, MSYS2 (itself a fork of Cygwin, a Unix-like emulation environment for Windows) and various other Windows ports or emulations of Linux utilities and libraries. Currently, native Windows builds of Git are distributed as 32- and 64-bit installers. The git official website currently maintains a build of Git for Windows, still using the MSYS2 environment. The JGit implementation of Git is a pure Java software library, designed to be embedded in any Java application. JGit is used in the Gerrit code-review tool, and in EGit, a Git client for the Eclipse IDE. Go-git is an open-source implementation of Git written in pure Go. It is currently used for backing projects as a SQL interface for Git code repositories and providing encryption for Git. Dulwich is an implementation of Git written in pure Python with support for CPython 3.6 and later and Pypy. The libgit2 implementation of Git is an ANSI C software library with no other dependencies, which can be built on multiple platforms, including Windows, Linux, macOS, and BSD. It has bindings for many programming languages, including Ruby, Python, and Haskell. JS-Git is a JavaScript implementation of a subset of Git. Game of Trees is an open-source implementation of Git for the OpenBSD project. git9 is an in

Screenshot of Gitweb interface showing a commit diff As Git is a distributed version control system, it could be used as a server out of the box. It is shipped with a built-in command git daemon which starts a simple TCP server running on the Git protocol. Dedicated Git HTTP servers help (amongst other features) by adding access control, displaying the contents of a Git repository via the web interfaces, and managing multiple repositories. Already existing Git repositories can be cloned and shared to be used by others as a centralized repo. It can also be accessed via remote shell just by having the Git software installed and allowing a user to log in. Git servers typically listen on TCP port 9418. Open source Hosting the Git server using the Git Binary. Gerrit, a Git server configurable to support code reviews and provide access via ssh, an integrated Apache MINA or OpenSSH, or an integrated Jetty web server. Gerrit provides integration for LDAP, Active Directory, OpenID, OAuth, Kerberos/GSSAPI, X509 https client certificates. With Gerrit 3.0 all configurations will be stored as Git repositories, and no database is required to run. Gerrit has a pull-request feature implemented in its core but lacks a GUI for it. Phabricator, a spin-off from Facebook. As Facebook primarily uses Mercurial, Git support is not as prominent. RhodeCode Community Edition (CE), supporting Git, Mercurial and Subversion with an AGPLv3 license. Kallithea, supporting both Git and Mercurial, developed in Python with GPL license. External projects like gitolite, which provide scripts on top of Git software to provide fine-grained access control. There are several other FLOSS solutions for self-hosting, including Gogs, Gitea, a fork of Gogs, as well as Forgejo, which is, in turn, a fork of Gitea. Gogs, as well as the two aforementioned derivatives of it, is deve

Git GUI clients offer a graphical user interface (GUI) to simplify interaction with Git repositories. These GUIs provide visual representations of project history, including branches, commits, and file changes. They also streamline actions like staging changes, creating commits, and managing branches. Visual diff tools help resolve merge conflicts arising from concurrent development. Git comes with a Tcl/Tk GUI, which allows users to perform actions such as creating and amending commits, creating and merging branches, and interacting with remote repositories. In addition to the official GUI, many 3rd party interfaces exist that provide similar features to the official GUI distributed with Git. GUI clients make Git easier to learn and use, improving workflow efficiency and reducing errors.

The Eclipse Foundation reported in its annual community survey that as of May 2014[update], Git is now the most widely used source-code management tool, with 42.9% of professional software developers reporting that they use Git as their primary source-control system compared with 36.3% in 2013, 32% in 2012; or for Git responses excluding use of GitHub: 33.3% in 2014, 30.3% in 2013, 27.6% in 2012 and 12.8% in 2011. Open-source directory Open Hub reports a similar uptake among open-source projects. Stack Overflow has included version control in their annual developer survey in 2015 (16,694 responses), 2017 (30,730 responses), 2018 (74,298 responses) and 2022 (71,379 responses). Git was the overwhelming favorite of responding developers in these surveys, reporting as high as 93.9% in 2022. Version control systems used by responding developers: Name 2015 2017 2018 2022 Git 69.3% 69.2% 87.2% 93.9% Subversion 36.9% 9.1% 16.1% 5.2% TFVC 12.2% 7.3% 10.9% [ii] Mercurial 7.9% 1.9% 3.6% 1.1% CVS 4.2% [ii] [ii] [ii] Perforce 3.3% [ii] [ii] [ii] VSS [ii] 0.6% [ii] [ii] IBM DevOps Code ClearCase [ii] 0.4% [ii] [ii] Zip file backups [ii] 2.0% 7.9% [ii] Raw network sharing [ii] 1.7% 7.9% [ii] Other 5.8% 3.0% [ii] [ii] None 9.3% 4.8% 4.8% 4.3% The UK IT jobs website itjobswatch.co.uk reports that as of late September 2016, 29.27% of UK permanent software development job openings have cited Git, ahead of 12.17% for Microsoft Team Foundation Server, 10.60% for Subversion, 1.30% for Mercurial, and 0.48% for Visual SourceSafe. Extensions There are many Git extensions, like Git LFS, which started as an extension to Git in the

Git can be used in a variety of different ways, but some conventions are commonly adopted. The command to create a local repo, git init, creates a branch named master. Often it is used as the integration branch for merging changes into. Some tools, such as GitHub and GitLab, create a default branch named main instead; Git itself will start using main from the 3.0 release, expected by the end of 2026. Since the default upstream remote is named origin, the default remote branch is origin/master. Also, users can add and delete branches and choose any branch for integrating. Pushed commits generally are not overwritten, but are reverted by committing another change which reverses an earlier commit. This prevents shared commits from being invalid because the commit on which they are based does not exist in the remote. If the commits contain sensitive information, they should be removed, which involves a more complex procedure to rewrite history. The git-flow workflow and naming conventions are often adopted to distinguish feature-specific unstable histories (feature/*), unstable shared histories (develop), production-ready histories (main), and emergency patches to released products (hotfix). A pull request, a.k.a. merge request, is a request by a user to merge a branch into another branch. Git does not itself provide for pull requests, but it is a common feature of git cloud services. The underlying function of a pull request is no different than that of an administrator of a repository pulling changes from another remote (the repository that is the source of the pull request). However, the pull request itself is a ticket managed by the hosting server which perform these actions; it is not a feature of git SCM.

Git does not provide access-control mechanisms, but was designed for operation with other tools that specialize in access control. On 17 December 2014, an exploit was found affecting the Windows and macOS versions of the Git client. An attacker could perform arbitrary code execution on a target computer with Git installed by creating a malicious Git tree (directory) named .git (a directory in Git repositories that stores all the data of the repository) in a different case (such as .GIT or .Git, needed because Git does not allow the all-lowercase version of .git to be created manually) with malicious files in the .git/hooks subdirectory (a folder with executable files that Git runs) on a repository that the attacker made or on a repository that the attacker can modify. If a Windows or Mac user pulls (downloads) a version of the repository with the malicious directory, then switches to that directory, the .git directory will be overwritten (due to the case-insensitive trait of the Windows and Mac filesystems) and the malicious executable files in .git/hooks may be run, which results in the attacker's commands being executed. An attacker could also modify the .git/config configuration file, which allows the attacker to create malicious Git aliases (aliases for Git commands or external commands) or modify extant aliases to execute malicious commands when run. The vulnerability was patched in version 2.2.1 of Git, released on 17 December 2014, and announced the next day. Git version 2.6.1, released on 29 September 2015, contained a patch for a security vulnerability (CVE-2015-7545) that allowed arbitrary code execution. The vulnerability was exploitable if an attacker could convince a victim to clone a specific URL, as the arbitrary commands were embedded in the URL itself. An attacker could use the exploit via a man-in-the-middle attack if the connection was unencr

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