arun-git.txt

Git ( vcs / SCM ) version control system / source code management.
 
Below are the functions of a VCS −

1. Allows developers to work simultaneously.

2. Does not allow overwriting each other’s changes.

3. Maintains a history of every version.


The Following are the types of VCS −

1. Centralized version control system (CVCS).  ===>> SVN

2. Distributed/Decentralized version control system (DVCS). ===> Git.

we will concentrate only on distributed version control system and especially on Git. Git falls under distributed version control system.

GIT ===>> alternative older VCS ==>> SVN.


Centralized version control system (CVCS) uses a central server to store all files and enables team collaboration.

 But the major drawback of CVCS is its single point of failure, i.e., failure of the central server. 

 Unfortunately, if the central server goes down for an hour, then during that hour, no one can collaborate at all.

 And even in a worst case, if the disk of the central server gets corrupted and proper backup has not been taken,

 then you will lose the entire history of the project. Here, distributed version control system (DVCS) comes into picture.

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DVCS clients not only check out the latest snapshot of the directory but they also fully mirror the repository.

If the server goes down, then the repository from any client can be copied back to the server to restore it. Every checkout is a full backup of the repository.

 Git does not rely on the central server and that is why you can perform many operations when you are offline.

 You can commit changes, create branches, view logs, and perform other operations when you are offline.
 
 You require network connection only to publish your changes and take the latest changes

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Git terminalogy :

Git is a client server architecture.

client  ===>> gitbash  and server.===>> github

repository : group of project files to store one single area and each project has one repository.==>>> github has ==>> n . no.of repositories..

cloning : remote reposiory ( myweb ) to getting the local ==>>> cloning ==>>> git clone url ( each project has one url) ===>> locally

fork : projects are copied from one github account to another github account.

local repository : getting the remote repository ( myweb) to our local laptop. 

remote repository : github ==>> our created  repository  ( myweb )

push : sending local repository changes  to remote repository 

pull : sending the remote repository changes to the local repository

Note : git follows ===>> 2 types of protocalls ==>>> https and ssh.

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Git workflow :

1. we need to clone remote repository to local..

git clone url 

git clone https://github.com/srinivas1987devops/myweb.git

ls

2. go to the inside local repository.

cd myweb

3. files ==>>> create / modify ===>> working area.

touch rk123

git status ==>> red color ==>> working area.

4. git add . / filename / *

git status

file ==>> green color ===>> INdexing / staging area.

5. we are getting the files to local repository ==>> commit

git commit -m 'rk2020' ==>> local repository.

git log

40 digits commitiD ==>>> head ==>> head always points to latest commit.

6. push to remote repository..

git push origin master

push ==>>> sending local changes to remote repository..

origin ==>> alias name ==>>> github url

master ==>> default branch.


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git config --global user.name “ramakrishnaj2020”

git config --global user.email “ramakrishnaj832@gmail.com”


git push origin master ==>> githubaccountname and github passsowrd ==>>> remote.

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How to undo changes in working area ??

file ==>> modify ==>> working area 

git checkout filename.

How to undo the changes in index/ staging area 

file ==>> modify ==>> working area 

git add . / filename / * ==>> index / staging area

git reset filename

How to undo the changes the in local repository.

file ==>> modify ==>> working area 

git add . / filename / * ==>> index / staging area.

git commit -m 'b123'

git log

git reset commitid 

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**** ===>>>> Branching strategies:<<===============

1. master branch ===>>> default branch

2. developement branch ( dev ) ==>>> every team has their own branch ==>> which is created from master branch.

3. feture branch ==>> every developer has their own branch ==>> which is created from dev branch.

4. hotfix / bugfix branch ==>> errors / bugs ===> which is created from master branch.===>> errors free ==>>> hotfix / bugfix branch will delete.

5. Release branch.===>> every release has one branch with version ==>> which is created from master branch. ==>> once release push to remote ==>>  Release branch will delete.

Branch : To develope the code of our project.

How to create branch in locally ??

git branch branchname

How to push local branch remote ???

git push origin branchname

How to delete local branch

git branch -d branchname

How to delete remote branch 

git push origin -d branchname

How to go to inside a branch

git checkout branchname

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***** merging strayegies in locally ****

1. fast-forward 

2. twoway or recursive merge

3. git rebase ( dangerous)

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git cherry-pick :

It picks a commit from one branch and applys it to another branch with out doing merge.

git cherry-pick commitid.

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How to merge the remote side changes ===>>> pull request.

pull request ==>> remote side branches ==>>> github ===>> in between the branches ==>> merging is nothing but pull request.

pull request ==>> TL / collegues ===>> approval ==>> merge pull request ==>> conform merge.

pull request ==>>> source and destination 

source ( right side ) and destination ( left side).

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tags : tags are used to release the application or code version or feture version.

list of tags to see ==>> git tag

how to create a tag locally ??

git tag tagname

git tag v1.0


how to push local tag to remote 

git push origin taganme

git push origin v1.0


tags are create on the perticular commit.

git tag tagname commitid 

tags are created from the master branch only..

how to delete a tag locally

git tag -d tagname

how to delete remote tags

git push origin -d tagname.

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git stash :

bhargavi ==>> developer ==>> mno file ==>>> working area , index area ===>> before going to commit ==>> P1 ( priority one task ==>>> 2 hours close) .

bharagavi ==>>> developer ==>>> mno file ==>>> tempararily save ==>> git statsh.

after completion of the p1 task ==>> tempararily save ==>> unstash ==>> after that commit.

git stash save ==>>> tempararily save 

git stash list ==>> stash {0}

git stash apply stashid stash {5} or git stash pop stashid stash {5} ==>> unstash

git commit -m 'c1'

git push origin master.

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merge conflicts ( locally )

ramakrishna ==>> developer

siva ===>> developer

both develoeprs are working on the same file ===>>> pqrs ===>> same line ==>> 151

siva ==>> developer ==>> dev branch ==>>> merge ==>>> unable to merge.

git merge tool

pqrs ==>> will open ==>> 151 <<   >> ==>> brackets ==>>> remove the brackets

pull request conflicts ( remote side)

sekhar ==>> developer

sundar ===>> developer

both develoeprs are working on the same file ===>>> mno ===>> same line ==>> 351

sundar ==>> developer ==>> dev branch ==>>> pullrequest ==>>> unable to pullrequest. ===>> resolve conflicats.

mergeconflicts ===>>> click this ==>>>> mno ==>>> open 

mno ==>> will open ==>> 351 <<   >> ==>> brackets ==>>> remove the brackets.

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1. release branch

2. pullrequest.

3. tags 

4. github ==>> backup.

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