# Git
# Reasons to use version control
- Have a record of what, when, whom and why you did something
- Snapshots of different development states
- Compare different versions of files
- Easily share work with others
- Integrate changes from others (merging)
- Mark finished product versions (tags)
- Try out new ideas (branches)
- Best practice and Industry standard
# Without Version Control
# Glossary
- Repository
- Stores complete history, branches, tags (and other meta-information)
- Working Copy
- Your “playground”, actual source code
- Commit / Revision
- A specific, single version/snapshot
- Branch
- A distinct line of development
# Distributed Version Control
- Every user has a full copy of the repository
- Repositories can be synchronized (push/fetch)
- Off-line access
# Git
- Started in 2005 by Linus Torvalds
- Used for Linux Kernel development - is still used
- Highly distributed
- Cryptographic integrity
# Install & Setup
- Install - https://www.git-scm.com
- Set user information
git config --global user.name 'Norbert Winkler'
git config --global user.email '[email protected]'# Cheat Sheet
https://education.github.com/git-cheat-sheet-education.pdf
# Creating Repositories
- Create a new local repository
$ cd path/to/project
$ git init
# or
$ git init new_dir
$ cd new_dir# Adding files
- ”staging”
- Adding new files
- Current state of the file is recorded
# add a new file foo.txt with contents 'bar'
$ >foo.txt echo 'bar'
git add foo.txt# Writing history
- Permanently save your work
- The seven rules of a great Git commit message
$ git commit -m "Showcased how to add files to git"# Updating Files
- Tell Git about new changes
- Same thing as adding new files (Git only cares about the content of files)
# add new content to foo.txt
$ >>foo.txt echo 'new content'
$ git add foo.txt
$ git commit -m 'updated file'# Browsing history
- Branch “master” == “main”
$ git log
commit 1238062398b6727455abe88e6b789ca041f62ecd (HEAD -> master)
Author: clemens-sch <[email protected]t>
Date: Thu Jun 20 08:23:22 2024 +0200
added second line. blablabla
commit 94c02addc225374619b842bca1cc34b5fc6df305
Author: clemens-sch <[email protected]t>
Date: Thu Jun 20 08:20:27 2024 +0200# Working copy status
- Shows list of modified, new and staged files
- Also reminds you of important commands
$ git status
On branch master
nothing to commit, working tree clean# Inspecting changes
- Show current changes
- Show differences between commits
- Show differences between branches
$ git diff
$ git diff HEAD~ HEAD
$ git diff branch1 branch2# What the fork?
- Try out new features
- In an ideal world: one branch per feature
- Branches are cheap, use them often
- Branches can be deleted
# create and switch to new branch
$ git branch newbranch
$ git checkout newbranch
# list branches (star marks active branch)
$ git branch
main
* newbranch# Merging changes
- Integrate changes from a branch
- Integrate changes from others
# Checkout the branch you want the changes to merge into
$ git checkout main
# merge changes from other branch
$ git merge newbranch# Merge conflicts
- Merges don’t always go well
- Git inserts conflict markers into conflicting files
git statustells you the current state- Remove conflicts and add that state of the file with
git add
$ git diff
diff --cc foo.txt
…
<<<<<<< HEAD
current content
=======
branch content
>>>>>>> newbranch
# manually resolve conflict
$ vim foo.txt
# add new state to git
$ git add foo
$ git commit# Forking existing projects
- Get a copy of the repository
fetch+mergeto update your copy
$ git clone https://github.com/git/git.git git
$ cd git
# ...
$ git fetch
$ git merge origin/branch# Syncing changes
- Fetch downloads the latest changes from the remote repository
- With merge you can merge these changes with your local branch
pullis a shortcut forfetch+mergepushuploads your local changes to the remote repository
$ git pull
# make changes and commit them ...
# afterwards:
$ git push