Git Lecture Notes

Topics Discussed

SSH, public key authentication.
Version Control
Git Basics
Git Workflow
Github
Extra git commands
Git GUI’s

SSH

Installing ssh

sudo apt-get install openssh

Connecting to server

$ ssh username@hostname

Public key authentication

ssh-keygen -t rsa The private key is at ~/.ssh/id_rsa while the public key is at ~/.ssh/id_rsa.pub The server needs your public key to authenticate the connection.

Version Control

central VCS v/s Distributed VCS
Why Version Control
- Helps remember history of project
- Move back and forth in history
- Any break in code can be fixed easily
- Any bugs introduced can be traced back to the code that made it
Examples : svn, cvs, mercurial, bzr, etc

Git Basics

This is just a simple walkthrough. You are encouraged to try out these steps on your own.

git init creates a new repository
git clone <url> [folder]clones a repo from the server
git add <filename> adds files to index
git add . adds everything to index
git commit creates a commit
git commit -a adds all modified files to the index and starts a commit
A blank commit message aborts the commit
git checkout <ref> changes your working directory to a commit/tag/branch
git checkout -b branchname creates a new branch and shifts to it
git branch shows a list of all branches & the current branch
git branch <branch> creates a new branch, but does not switch to it
git merge branchname merges the branch with the current branch
git tag marks a tag for the current commit

A Little More

git pull [remote] [ref] fetches and merges the branch/commit with the current HEAD
git fetch [remote] [ref] fetches the commits for merging
Therefore, pull = fetch + merge
Similarly, checkout -b = branch + checkout //Create and checkout

Little of git-jargon

Git Workflow

Fork, Merge, Pull

This is what Github follows. People create their own fork version of the repo, and send back pull requests

Shared Repository

A single repository shared among various people can be used successfully if the project is closed, and has known developers This is mainly for organizations and trusted developers

Branching Model

Mainly from here
Topics include branches, stable, hotfix, release, development, feature branch etc.

Github

http://github.com is an awesome site that allows people to share code, projects and collaborate easily using git.
Create an account
Setting up ssh-keys
Creating repository
Setting remotes
push, pull, fetch, merge
Github gem
Online Editing as well (press e on a file)

Some other things

A few more git commands

git log allows you to see your history
git log --oneline gives single line history
git log --pretty gives better output
git log --graph shows your commit graph
Git GUI Systems - gitg, git-cola, qgit, giggle and the windows git-gui as
Mac - Gitbox, SourceTree, Github for Mac
.gitignore file to store system specific stuff (configuration, databases, temp files, cache, build)
tig is an awesome commit browser that runs on the command line.

To install any of the packages mentioned above, just run sudo apt-get install package in ubuntu.

Redmine

Create user accounts (Registration)
git config user.name and git config user.email should be setup
Pass along the public keys (via email)

Commit Messages Editing

When you make commits on git, it uses your default text editors to type the commit message. This is set to vim in Windows and Linux. Linux folks can change it to anything else by setting the $EDITOR variable by the following command: export EDITOR=nano (Replace nano with the editor of your choice like gedit geany etc)

You can also save the setting in your git global configuration, by : git config --global core.editor "nano"

As per this question on SO, you can use Notepad++, or notepad etc on git on Windows as well.

git config --global core.editor "'C:/Program Files/Notepad++/notepad++.exe' -multiInst -notabbar -nosession -noPlugin"

Take care about the slashes, and the path to your editor of choice. Don’t use notepad, it screws with the newlines.

Vim

If you’re stuck with vim for some reason, do the following in the commit window

Press i to go to insert mode
Type your commit message
Press Esc
Type :wq. The colon is important
Press Enter
That’s it, your commit should be successful

Remember, an empty commit message aborts the commit. Also the best way to commit easily is:

git commit -m "Commit Message Here" to just type the commit message on the command line, and leave out all the hassle of the editor

To learn how to use vim effectively, type ‘vimtutor’ in terminal.

Faster Git Resources

Git allows you to defined aliases for certain commands. These faster ways of using git create several additional commands for git, such as git release, and ga etc

SCM Breeze #awesome
Git Extras
Git Aligned Logs
Git-Number - Similar to SCM Breeze

Also see tig, which is a cli repo browser for git.