git

Introduction to GIT

Git store data as snapshots of the project over time. Git is check-summed before it is stored and is then referred to by that checksum. The mechanism that Git uses for this checksumming is called a SHA-1 hash. This is a 40-character string composed of hexadecimal characters (0–9 and a–f): 24b9da6552252987aa493b52f8696cd6d3b00373

Git has three main states that your files can reside in: modify, commit, and stage.

• The working directory (modify) is a single checkout of one version of the project. These files are pulled out of the compressed database in the Git directory and placed on disk for you to use or modify.
• The staging area (stage or index) is a simple file, generally contained in your Git directory, that stores information about what will go into your next commit. It’s sometimes referred to as the index, but it’s becoming standard to refer to it as the staging area.
• The Git directory (Commit, local or remote) is where Git stores the metadata and object database for your project. This is the most important part of Git, and it is what is copied when you clone a repository from another computer.

The basic Git workflow goes something like this:

1. You modify files in your working directory.
2. You stage the files, adding snapshots of them to your staging area.
3. You do a commit, which takes the files as they are in the staging area and stores that snapshot permanently to your Git directory.

Git Configuration can be stored in three different locations:

• /etc/gitconfig file: Contains values for every user on the system and all their repositories. If you pass the option --system to git config, it reads and writes from this file specifically.
• ~/.gitconfig file: Specific to your user. You can make Git read and write to this file specifically by passing the --global option.
• config file in the git directory (that is, .git/config) of whatever repository you’re currently using: Specific to that single repository. Each level overrides values in the previous level, so values in.git/config trump those in /etc/gitconfig.

Git Commands

Initial Setup

Show help for a command

git help command

git command --help

Cloning a project (get a copy of a project):

git clone [ssh://, http(s)://, git://]/URLS/path/to/file.git

For example:

git clone git://git.kernel.org/pub/scm/git/git.git

Initialize a new repository:

git init

File Operations

Add file or files in directory recursively:

git add path

Remove file or directory from the working tree

git rm path

Showing differences between working and local repository:

git diff

Showing the differences between working and index:

git diff --cached

Show the brief summary of the situation:

git status

Commit from index to local repository, if you have not added to the index repository, it won't be committed:

git commit [file,directory]

Commit from working straight to local repository:

git commit -a [file,directory]

Branch Operation

Show the local branches:

git branch

Show all branches including the remote repository:

git branch -a

Get a copy of the Entire remote repository without merging them into your local:

git fetch origin

Create a remote branch on the GIT server using the master refs:

git push origin origin:refs/heads/NEW_BRANCH_NAME

Create a remote branch on the GIT server using some other branch refs:

git push origin origin/SOME_BRANCH_NAME:refs/heads/NEW_BRANCH_NAME

Check out the new branch and track it on the localhost:

git checkout --track -b NEW_BRANCH_NAME origin/NEW_BRANCH_NAME

Remove a remote branch on the GIT server:

git push origin :heads/BRANCH_NAME

Remove the remote branch from your localhost:

git branch -r -d origin/BRANCH_NAME

Remove the unmerge local branch on the localhost:

git branch -D BRANCH_NAME