GIT(Global Information Tracker)
- In this blog , we learn about what is Git ? why we use Git ? and what are some basic commands that we have to learn as a Software Engineer ?
What is Git ?
Git is an open source distributed version control system that is available for free under the GNU General Public License version, The Git source code is hosted on GitHub from where it can be downloaded or installed.
By far, the most widely used modern version control system in the world today is Git. Git is a mature, actively maintained open source project originally developed in 2005 by Linus Torvalds, the famous creator of the Linux operating system kernel. A staggering number of software projects rely on Git for version control, including commercial projects as well as open source. Developers who have worked with Git are well represented in the pool of available software development talent and it works well on a wide range of operating systems and IDEs (Integrated Development Environments).
Having a distributed architecture, Git is an example of a DVCS (hence Distributed Version Control System). Rather than have only one single place for the full version history of the software as is common in once-popular version control systems like CVS or Subversion (also known as SVN), in Git, every developer’s working copy of the code is also a repository that can contain the full history of all changes.
Why we use Git ?
In addition to being distributed, Git has been designed with performance, security and flexibility in mind.
Performance
The raw performance characteristics of Git are very strong when compared to many alternatives. Committing new changes, branching, merging and comparing past versions are all optimized for performance. The algorithms implemented inside Git take advantage of deep knowledge about common attributes of real source code file trees, how they are usually modified over time and what the access patterns are.
Unlike some version control software, Git is not fooled by the names of the files when determining what the storage and version history of the file tree should be, instead, Git focuses on the file content itself. After all, source code files are frequently renamed, split, and rearranged. The object format of Git’s repository files uses a combination of delta encoding (storing content differences), compression and explicitly stores directory contents and version metadata objects.
Being distributed enables significant performance benefits as well.
For example, say a developer, Saurabh, makes changes to source code, adding a feature for the upcoming 2.0 release, then commits those changes with descriptive messages. he then works on a second feature and commits those changes too. Naturally these are stored as separate pieces of work in the version history. Saurabh then switches to the version 1.3 branch of the same software to fix a bug that affects only that older version. The purpose of this is to enable Saurabh ’s team to ship a bug fix release, version 1.3.1, before version 2.0 is ready. Saurabh can then return to the 2.0 branch to continue working on new features for 2.0 and all of this can occur without any network access and is therefore fast and reliable. he could even do it on an airplane. When he is ready to send all of the individually committed changes to the remote repository, Saurabh can “push” them in one command.
Security
Git has been designed with the integrity of managed source code as a top priority. The content of the files as well as the true relationships between files and directories, versions, tags and commits, all of these objects in the Git repository are secured with a cryptographically secure hashing algorithm called SHA1. This protects the code and the change history against both accidental and malicious change and ensures that the history is fully traceable.
With Git, you can be sure you have an authentic content history of your source code.
Some other version control systems have no protections against secret alteration at a later date. This can be a serious information security vulnerability for any organization that relies on software development.
Flexibility
One of Git’s key design objectives is flexibility. Git is flexible in several respects: in support for various kinds of nonlinear development workflows, in its efficiency in both small and large projects and in its compatibility with many existing systems and protocols.
Git has been designed to support branching and tagging as first-class citizens (unlike SVN) and operations that affect branches and tags (such as merging or reverting) are also stored as part of the change history. Not all version control systems feature this level of tracking.
Some Basic Command
Here are some Git commands which are mostly used :
git init
Usage: git init [repository name]
The git init command creates a new Git repository. It can be used to convert an existing, unversioned project to a Git repository or initialize a new, empty repository. Most other Git commands are not available outside of an initialized repository, so this is usually the first command you’ll run in a new project.
git remote add -> git remote add (remote_name) (URL)
To add a new remote, use the git remote add command on the terminal, in the directory your repository is stored at. The git remote add command takes two arguments: A unique remote name, for example, “my_awesome_new_remote_repo” A remote URL, which you can find on the Source sub-tab of your Git repo.
git config
Usage: git config –global user.name “[name]”
Usage: git config –global user.email “[email address]”
The git config command is a convenience function that is used to set Git configuration values on a global or local project level. These configuration levels correspond to . gitconfig text files. Executing git config will modify a configuration text file.
git clone
Usage: git clone [url]
This command is used to obtain a repository from an existing URL.
git add
Usage: git add [file]
This command adds a file to the staging area.
Usage: git add *
This command adds one or more to the staging area.
git commit
Usage: git commit -m “[ Type in the commit message]”
This command records or snapshots the file permanently in the version history.
Usage: git commit -a
This command commits any files you’ve added with the git add command and also commits any files you’ve changed since then.
git diff
Usage: git diff
This command shows the file differences which are not yet staged.
Usage: git diff –staged
This command shows the differences between the files in the staging area and the latest version present.
sage: git diff [first branch] [second branch]
This command shows the differences between the two branches mentioned.
git reset
Usage: git reset [file]
This command unstages the file, but it preserves the file contents.
Usage: git reset [commit]
This command undoes all the commits after the specified commit and preserves the changes locally.
Usage: git reset –hard [commit] This command discards all history and goes back to the specified commit.
git status
Usage: git status
This command lists all the files that have to be committed.
git rm
Usage: git rm [file]
This command deletes the file from your working directory and stages the deletion.
git log
Usage: git log
This command is used to list the version history for the current branch.
Usage: git log –follow[file]
This command lists version history for a file, including the renaming of files also.
git show
Usage: git show [commit]
This command shows the metadata and content changes of the specified commit.
git tag
Usage: git tag [commitID]
This command is used to give tags to the specified commit.
git branch
Usage: git branch
This command lists all the local branches in the current repository.
Usage: git branch [branch name]
This command creates a new branch.
Usage: git branch -d [branch name]
This command deletes the feature branch.
git checkout
Usage: git checkout [branch name]
This command is used to switch from one branch to another.
Usage: git checkout -b [branch name]
This command creates a new branch and also switches to it.
git merge
Usage: git merge [branch name]
This command merges the specified branch’s history into the current branch.
git push
Usage: git push [variable name] master
This command sends the committed changes of master branch to your remote repository.
Usage: git push –all [variable name]
This command pushes all branches to your remote repository.
sage: git push [variable name] :[branch name]
This command deletes a branch on your remote repository.
git pull
Usage: git pull [Repository Link]
This command fetches and merges changes on the remote server to your working directory.
git fetch
This command fetches all the changes on the remote server to your working directory.
git rebase
Rebasing is the process of moving or combining a sequence of commits to a new base commit. Rebasing is most useful and easily visualized in the context of a feature branching workflow.