GIT - The Simple Guide

Just a simple guide for getting started with git. It shows how to use terminal or command lines to create, add, commit, branching, tags etc easily by following simple guides described as following.

Create a new repository
create a new directory, open it and perform a

  git init

to create a new git repository.

Checkout a repository
Create a working copy of a local repository by running the command

  git clone /path/to/repository

when using a remote server, your command will be

  git clone username@host:/path/to/repository

Workflow
Your local repository consists of three "trees" maintained by git. the first one is your Working Directory which holds the actual files. the second one is the Index which acts as a staging area and finally the HEAD which points to the last commit you've made.

Add & commit
You can propose changes (add it to the Index) using

 git add <filename>
 git add *

This is the first step in the basic git workflow. To actually commit these changes use

 git commit -m "Commit message"

Now the file is committed to the HEAD, but not in your remote repository yet.

Pushing changes
Your changes are now in the HEAD of your local working copy. To send those changes to your remote repository, execute

git push origin master

Change master to whatever branch you want to push your changes to.
If you have not cloned an existing repository and want to connect your repository to a remote server, you need to add it with

git remote add origin <server>

Now you are able to push your changes to the selected remote server

Branching
Branches are used to develop features isolated from each other. The master branch is the "default" branch when you create a repository. Use other branches for development and merge them back to the master branch upon completion.

create a new branch named "feature_x" and switch to it using

git checkout -b feature_x

switch back to master

 
 git checkout master

and delete the branch again.

 git branch -d feature_x

A branch is not available to others unless you push the branch to your remote repository

 git push origin <branch>

Update & merge
To update your local repository to the newest commit, execute

git pull

in your working directory to fetch and merge remote changes.
To merge another branch into your active branch (e.g. master), use

git merge <branch>

in both cases git tries to auto-merge changes. Unfortunately, this is not always possible and results in conflicts. You are responsible to merge those conflicts manually by editing the files shown by git. After changing, you need to mark them as merged with

 git add <filename>

before merging changes, you can also preview them by using

 git diff <source_branch> <target_branch>

Tagging
Tt's recommended to create tags for software releases. this is a known concept, which also exists in SVN. You can create a new tag named 1.0.0 by executing

git tag 1.0.0 1b2e1d63ff

the 1b2e1d63ff stands for the first 10 characters of the commit id you want to reference with your tag. You can get the commit id by looking at the...

Replace local changes
In case you did something wrong, which for sure never happens ;), you can replace local changes using the command

 git checkout -- <filename>

this replaces the changes in your working tree with the last content in HEAD. Changes already added to the index, as well as new files, will be kept.
If you instead want to drop all your local changes and commits, fetch the latest history from the server and point your local master branch at it like this

 git fetch origin
 git reset --hard origin/master

Source : git - the simple guide