Getting Started With Git

Git

     As web developers, a lot of times we work/develop application in local system then just upload everything to server when we are done. This is fine when single developer or doing small changes in the code, but when we are dealing with more than one person working on something or large project. That’s simply not feasible. So, we are turning to Version Control.

      This article main focusing on Git basic command to setup and handle the code in Git Version Control.

What is Version Control System?
     A version control system allows you to track the history of a collection of files and includes the functionality to revert the collection of files to another version. The collection of files is usually source code for a programming language but a typical version control system can put any type of file under version control.

What is Git?

      Git is a free and open source distributed version control system. A distributed version control system does not necessarily have a central server which stores the data.

     The user can copy an existing repository. This copying process is typically called cloning in a distributed version control system. Typically there is a central server for keeping a repository but each cloned repository is a full copy of this repository in your local system.

Git vs. SVN

     Here are going to discuss the few of the difference between SVN and Git version control system.

1)      Git is distributed Version Control System

2)      You can save/commit your local file change and create new branch without have network connection.

3)      Git is stored the changes like content as metadata, svn stored just files

4)      SVN creates .svn directories in every single folder (Git only creates one .git directory)

5)      You have to tell SVN whenever you move or delete something. Git will just figure it out.

6)      Ignore semantics are easier in Git. If you ignore a pattern (such as *.pyc), it will be ignored for all subdirectories. (But if you really want to ignore something for just one directory, you can). With SVN, it seems that there is no easy way to ignore a pattern across all subdirectories

Git Terminology
     The following table provides a major Git terminology

Term	Description
Clone	Clone the existing repository in git
Add	When add your new/updated file to be added to staging area
Commit	When you commit your changes files (Added files) in your local repository
Push	Push will move the committed, list of files to the remote git repository
Pull	Pull updated the others committed files in your local.
Branches	A branch is a named pointer to a commit. Selecting a branch in Git terminology is called to checkout a branch.
Tags	A tag points to a commit which uniquely identifies a version of the Git repository. With a tag, you can have a named point to which you can always revert to. You can revert to any point in a Git repository, but tags make it easier. The benefit of tags is to mark the repository for a specific reason, e.g., with a release. Branches and tags are named pointers; the difference is that branches move when a new commit is created while tags always point to the same commit.

Git Global Configuration

     Before go to start the creating new repository or project in git. We need to set the global variable configuration (.gitconfig). It will author helpful to tracking the history of the file changes in git.

     

     In each Git repository you can also configure the settings for this repository. Global configuration is done if you include the --global flag, otherwise your configuration is specific for the current Git repository.

     To setup the configuration use the git config command

Git Global Configuration

     Before go to start the creating new repository or project in git. We need to set the global variable configuration (.gitconfig). It will author helpful to tracking the history of the file changes in git.
     
     In each Git repository you can also configure the settings for this repository. Global configuration is done if you include the --global flag, otherwise your configuration is specific for the current Git repository.
     
     To setup the configuration use the git config command

     # configure the user which will using this git
     git config --global user.name "your name"

     # user email address for using this git
     git config --global user.email "your.email@gmail.com"
   
     # proxy configuration setting
     git config --global http.proxy http://<corpusername>:<corppassword>@<proxyaddress>

Cloning remote repositories
     You can use the git clone command to clone existing repositories in git (Github or Gitlab).

     # clone the remote repositories (Master) in local system
     git clone <HTTP/HTTPS/SSH Clone Url >

     # clone the particular branch from git repository     git clone <HTTP/HTTPS/SSH Clone Url > -b <branch-name> --single-branch

     Every clone contains the full history of the files and a cloned repository has the same functionality as the original repository.

Git Status

     Git status command is help to show current status of the current branch. What are the files are changed, new added, conflicts and removed.

     # show the status of the current branch
     git status

Adding changes to your Git Repository

     You add changes in the working tree to the staging area with using git add command. The git add command allows you to incrementally modify files and stage them. Until you are complete your tasks.

     # Staging all the modified files
     git add -A

     # if you need to staging only the particular files. Add multiple files with space
     git add <filepath/filename><space><filepath/filename>

     # Here we are added test.php and test1.py files to staging
     git add testfolder/test.php testfolder2/test1.py

Committing to the repository

     After adding selected file to the staging, you can commit those files permanently to the git repository. Committing create new persistent snapshot called commit or commit object.

     # Commit the files with short message
     git commit –m “Type the short message to under that commit purpose”

Git Pull

     The get pull command will help to get the latest updated from other people of the branch.

     # pull the updated code from remote
     git pull origin <branch name>

     When pulling the updated code from origin (Remote Repository), if someone worked on the same file.  You may be end up with the conflict file. In that case you need to solved the conflict file and push to the remote repository.

Git Push     

     Git push command is use to publishing your local changes (local commit) to the remote repository. 

     # pushing the local commit files to remote
     git push origin <branch name>

Git Branch

     You can create new branch and work on independently from each other. Default branch most often called master.

     You can create branch regular basis. Whenever working on new functionality/features.

     # list all the local branch names
     git branch

     #Output Current branch name with highlighted with (*) 
    * develop
       feature-optimization
       feature-rights-integration
       feature-usergroup
       master

     # listing all the local and remote branch names
     git branch -a

     # listing all the remote branches names
     git branch -r

     The –v option list more information about the local branch (Display with last commit message and commit id)

Create Branch

     Create a new branch using git branch <branch name> command. This command allows specifying the starting point (commit id, tag, remote or local branch). If not specified the commit to which the HEAD reference points is used to create the branch.

     # create new branch

     git branch <branch name>

     Your local git repository contains references to the branches on the remote repositories to which it is connected. This is call remote tracking branches.

     Create new tracking branches by specifying the remote branch during the creation of a branch.

     # create a tracking branch called ‘testbranch’
     # which tracks origin/testbranch

      git branch testbranch origin/testbranch

     To see the tracking branches of the remote repository use the below command

     # show all remote and tracking branches for origin
      git remote show origin

Checkout Branch

     To start working in a branch first you have to ‘checkout’ the branch. If you checkout a branch, the HEAD pointer moves to the last commit in that branch.

     # Switch to your new branch ‘testbranch’
      git checkout testbranch

     Instead of two step create and checkout to the branch. You can directly create a branch and checkout to that branch using “git checkout –a” command

     # create branch and switch to it
      git checkout –b <branch name>

Rename a Branch

     # rename a branch

     git branch –m <old branch name> <new branch name>

Delete a Branch

     To delete any branch, first you need to make sure you are not in that branch currently and that branch should not have any uncommitted changes.

     # delete a local branch
     git branch –d <branch name>

     #Force to delete the branch

     git branch –D <branch name>

     Delete the branch in a remote repository using the following command,

     # Delete the branch in remote repository
      git push origin : <branch name>

     #Alternative command

     git push origin - - delete :<branch name>

Differences between branches

     # Differences between two branches

      git diff <branch name1> <branch name2>

Git Merge

     Git Merge allows you to combine the change of the two branches. Git Merge command is merge the branch to your current checkout branch only.

     # Merges into your currently checked out branch
      git merge <branch name>

     #Eg. I need to merge develop branch to master branch

     #Step 1 checkout to master branch
     git checkout master

     #Step 2 Merge develop branch
     git merge develop

Git Ignore

     Git has provided the option to add the files and directories to ignore list. The .gitignore file tells Git to ignore the specified files in Git commands. You can still add ignored files to the staging area of the Git repository by using the --force parameter, i.e. with the git add --force [filename] command.

     This is useful if you can add the auto-generating log files, local server database, proxy and mail server configuration files.

     You can also revert back those files whenever you need, using “—no-assume-unchanged”

     # add files to ignore list
     git update-index –assume-unchanged <files list>

     #Eg. I need to add database.php and error_log.txt in Ignore list
     git update-index –assume-unchanged database.php error_log.txt

     # Revert back the ignore list files
     git update-index --no-assume-unchanged <files list>

Git log

     The git log command shows the history of your repository in the current branch, i.e. the list of commits.

     # show the history of commits in the current branch
      git log

     # filter the log output by a certain author
     git log --author=<authorename>

Tags in Git

     Git has the option to tag a commit in the repository history so that you find it easier at a later point in time. Most commonly, this is used to tag a certain version which has been released.

     If you tag a commit, you create an annotated or lightweight tag. Git supports two different types of tags, lightweight and annotated tags. 

     A lightweight tag is a pointer to a commit, without any additional information about the tag.

     An annotated tag contains additional information about the tag, e.g. the name and email of the person who created the tag, a tagging message and the date of the tagging.

Annotated tags can also be signed and verified with GNU Privacy Guard (GPG).

     # List the available tags

     git tag

     # Create the lightweight tags
     git tag <tagname>

     #Create annotated tags
     git tag <tagename> -m “<tag note>”

     #Create tags for a certain commit id
     git tag <tagename> -m “<tag note>” <commit id>

Thanks You Guys :-)