Git is a distributed source control system, that is lighting fast and different from client-server systems. In this tutorial, we will learn how to get started with Git. By the end of this tutorial, you should be able to create a Git repository, record snapshots of your project for safekeeping, and view your project's history.
Setup
Download git from the following locations:
Create a new repository
create a new directory, and perform the following operation to create a new git repository.
git init
Executing git init creates a .git subdirectory in the project root, which contains all of the necessary metadata for the repo.
Aside from the .git directory, an existing project remains unaltered (unlike SVN, Git doesn't require a .git folder in every subdirectory).
Checkout a repository
create a working copy of a local repository by running the following 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 3 trees maintained by git:
- Working Directory which holds the actual files
- Index/Staging which acts as a staging area
- 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>
This is the first step in the basic git workflow. To actually commit these changes use
git add *
Now the file is committed to the HEAD, but not in your remote repository yet.
git commit -m "Commit message"
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
It'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 3a5e1d87af
The 3a5e1d87af 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 log.
Logging
You can study repository history using:
git log
You can add a lot of parameters to make the log look like what you want. To see only the commits of a certain author:
git log --author=sean
To see a very compressed log where each commit is one line:
git log --pretty=oneline
Or mabe you want to see an ASCII art tree of all the branches, decorated with the names of tags and branches:
git log --graph --oneline --decorate --all
See only which files have changed:
git log --name-status
These are just a few of the possible parameters you can use. For more, see
git log --help
Replace local changes
In case you did something wrong, 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
Useful commands
Here are few more useful git commands:
Built-in git GUI
gitk
Use colorful git output
git config color.ui true
Show log on just one line per commit
git config format.pretty oneline
Use interactive adding
git add -i