Intro to Git
Version Control
- Version Control System - Version control tracks changes allowing you to see, and revert back to, previous versions as well as track the individuals who make them.
- Local Version Control - One database on your hard disk that stores changes to files.
- Centralized Version Control - A single server that stores all changes and file versions. Useful when working in teams.
- Distributed Version Control - Allows clients to create mirrored repositories. Gives more backup options than CVCS.
What’s Git?
A DVCS that creates a snapshot of the files, and stores a reference to it, when you commit (save) changes. Git relies on local operations, which speeds the process because a projects history is stored on the local disk, so it wont have to connect to servers. Git tracks all changes and detects file corruption minimizing lost data and makes it difficult for committed snapshots to be lost. There are three main states to Git, committed; data is securely stored in local database, modified; file is changed but not committed, and staged; flagged a files changed version to be committed in the next snapshot.
Lets get started
Download Git
Mac OS X - This can be downloaded using the Terminal, simply try to run Git and if it is not installed it will prompt you to install. You can also download through Git Website or GitHub.
Windows - Through the Git Website or GitHub Site.
Linux - Through the Package Manager with Fedora: sudo yum install git, or with Ubuntu: sudo apt-get install git. Another option is the Git Website.
Setup
Git comes with Graphical User Interface (GUI) tools but there are also third part options called GUI Clients. Mac, Windows and Linux systems can download GUI Clients Here.
Configuration of Variables - git config allows the setting of configuration variables that control aspects of Git’s operation and look.
Identity Setting - Set Username In the Terminal or Command line type: git config --global user.name "Jane Smith" and then git config --global user.email "example@email.com". Check the settings by entering: git config --global user.name (should return Jane Smith) and git config --global user.email (should return example@email.com). Using the –global option sets that option for the whole system, for specific projects enter the desired Git repository instead.
Default Text Editor - Unless configured with a default text editor, Git will use the systems. If you wanted to set a different text editor, for example Emacs, you would type git config --global core.editor emacs into your command line.
Checking settings - Use git config --list to get a list of your current settings.
Getting Help - This can be done one of three ways.
Setting up a Git Repository
Importing
You can import an existing project or directory into Git by following these steps:
- Switch to the target project’s directory.
cd test (cd = change directory)
- Use git init.
git init
- Start tracking these repository files by forming an initial commit.
git add *.cgit add LICENSEgit commit -m "any message here"
The files are now tracked and there is an initial commit.
Cloning
The clone command git clone https://github.com/test is used to make a copy of an existing Git repository by adding its URL. When you clone a file you copy all versions of all files for the project. This creates a directory called test with an initialized .git directory inside it. The command will also check out a copy of the newest version of the project. To clone a repository into a directory with a name of your choosing use: git clone https://github.com/test mydirectory. This makes a copy of the target repository in a directory named “my directory”.
Workflow
Local Repository Structure
The local Git repository has three components. The Working Directory is where the actual files reside, the Index is the area used for staging and the Head points to the most recent commit.
Saving Changes
All files in a working copy of a project file are either in a tracked or untracked state.
Tracked files can be modified, unmodified or staged; they were part of the most recent file snapshot. Untracked files were not in the last snapshot and are not currently in the staging area.
After cloning a repository, files have a tracked status and are unmodified because they have been checked out but not edited.
Checking File Status
The git status command will show the state of files. This will tell you which branch you are on as well as tracked, “working directory clean”, or untracked.
Tracking and Staging a New File
You can track a single file with the command git add filename or all files with git add *. After using these the files are tracked and staged for committing.
You can see information regarding changes after adding a new file by using the git status command.
Committing Files should be done after staging them using git commit -m “made change x,y,z” it is always a good idea to leave detailed messages about your changes. If you want to commit all files you would use git commit -a.
Pushing Changes
Pushing changes to a remote repository is done using git push origin master, this pushes changes from the local master branch to remote repository named origin. For cloned repositories Git gives the name origin to the server that was cloned and master to the local repository. These can be changed if desired.
Stashing Changes
The command git stash will remove and hide changes and git stash apply will retrieve them when ready to continue working.
Remote Repositories
When working in teams you will need to use remote repositories which reside online or on a network. This allows teams to push and pull information.
Seeing Your Remotes
The git remote command allows you to see the short names of all specified remote handles.
The git remove -v lets you view all remote URLs next to their short names.
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