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Git Summary

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1. Overview

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Sources used

• The missing semester Git lecture (made available by MIT).
• Pro Git book (freely available).
• Git manual.

Introduction

Git is a Distributed Version Control System (DVCS). It uses a directed acyclic graph (DAG) to model history (i.e., it supports branching):

o <-- o <-- o <-- o
              ^  
               \
                --- o <-- o

Snapshots are modeled as follows:

<root> (tree)
  |
  +- foo (tree)
  |  |
  |  + bar.txt (blob, contents = "hello world")
  |
  +- baz.txt (blob, contents = "git is wonderful")

All snapshots are identified either by their SHA-1 hashes or their references (e.g., “master”).

Git main areas

2. Essential Commands

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Setting up Git

1. Install

$ sudo apt install git

2. Configure

$ git config --global user.name "your name"
$ git config --global user.email "your email"
$ git config --global core.editor "your favourite text editor"

3. Check configuration

$ git config --list

4. Help

$ git help [command]

Setting your repository

Option 1: Clone from an existing repository

# full clone
$ git clone <URL ending with .git>

# shallow clone
$ git clone --depth=1 <URL ending with .git>

Option 2: Initialize your own repository

# initialize repo
$ git init

# specify which files / directories to ignore
$ vim edit .gitignore

# check log, current status, difference
$ git log [--all --graph --decorate]
$ git status
$ git diff [filename]

# stage files
$ git add <filename, leading directory, or use --all>

# commit changes
$ git commit



#######################################################
# Optional: linking to a remote server (such as github)
#######################################################

# link to a remote repo and verify
$ git remote add [-t branch] <name, usually called "origin"> <URL>
$ git remote -v

# push changes to remote repo
$ git push <remote name, normally "origin"> <local branch, normally "master">[:<remote branch>]

Branching and merging

# show existing branches
$ git branch

# create and step into the new branch
$ git branch <new branch name>
$ git checkout <branch name>

# merge current branch with a specified branch
$ git merge <branch to merge with>

# deleting a branch
$ git branch --delete <branch name>

Stashing

# ... hack hack hack ...
$ git stash
# make emergency fix
$ git commit -a -m "Fix in a hurry"
$ git stash pop
# ... continue hacking ...

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