An introduction to version control with git

A presentation made at Colorado State University's ACM club introducing students to version control using git.

Transcript

1. An introduction to version control with Connor Shea, GitLab
2. Goals • Introduce the concepts of version control and Git • Show the basics of using Git • Demonstrate some basic use-cases
3. What is Git? “I’m an egotistical bastard, and I name all my projects after myself. First Linux, now git.” - Linus Torvalds
4. What is Git? • Originally created in April 2005 by Linus Torvalds for developing Linux • Free and open source distributed version control system • Designed to be fast, fully distributed, and simple
5. What is “version control”? • Tracks changes to a project • Allows reverting to previous states • Makes collaboration easier • Keeps code backed up
6. Centralized Version Control Systems • CVS (1990), SVN (2000) • Codebase stored on a central server • Clients must connect to the server to check out revisions • Single point of failure
7. Decentralized Version Control Systems • Git (2005), Mercurial (2005) • No single central server • Each client gets a full copy of the repository, so everyone has their own “backup”
8. Why not work on projects using $OTHER_SYSTEM?
9. Is Git hard to use?
10. Yes, it sucks and I hate it.
11. https://xkcd.com/1597
12. Who uses Git?
13. A few small companies…
14. If it’s bad, why do people use it?
15. Because I lied, it’s good.
16. Because I lied, it’s good. • Handles huge projects really well • Linux: 693,323 commits, 14,000 contributors • GitLab: 59,191 commits, 1,300 contributors • Python: 99,820 commits, 347 contributors • Rails: 64,581 commits, 3,374 contributors • Swift: 58,445 commits, 505 contributors • Windows: Probably pretty big
17. Because I lied, it’s good. • Branches let contributors work on different features simultaneously. • Branches let contributors work on fixing bugs in older versions of software. • Repositories stay small, Linux’s repo is only 7GB. • Git is fast. Changing lots of files, deleting branches, making commits, etc. all take only a few seconds even for huge projects.
18. Because I lied, it’s good. • You can look at the history of a codebase, and even revert back to an older version. • Most modern developer tooling is built around Git • SCMs like GitLab and GitHub. • Continuous Integration tools like GitLab CI, Jenkins, etc. • IDEs like Eclipse, IntelliJ, Visual Studio, etc. • Hosting platforms like DigitalOcean and Heroku.
19. Because I lied, it’s good. • It’s very difficult to change the history of a repository. • Git commits are represented using SHA hashes, if you change a commit from last week, every commit after that will have a different SHA hash as well.
20. Downsides • It can be very difficult, frustrating to learn. • Requires frequently looking at tutorials, help pages, etc. • Certain commands can cause you to possibly lose data. • It’s not great for binary files like images, videos, 3D models, etc.
21. If you get stuck, that’s normal.
22. Examples
25. Installing Git See git-scm.com for instructions
26. Key Concepts
27. Repository The overarching “container” for all the code, commits, branches, etc.
28. Most common setup
29. Branches Split a branch off from the master branch.
30. Branches
31. Commit A set of changes to a codebase.
32. Pull Requests/Merge Requests Requesting code to be merged into a project.
34. Commands
35. git init Create a new repository.
36. git checkout Switch to another branch.
37. git add Add new files to the repository so they can be committed.
38. git commit Add changed files to the current branch.
39. git log See the commit history.
40. git blame See what commit and author last modified each line of a file.
41. git status git diff See what you’re in the middle of doing.
42. git reset Undo any changes that haven't been committed.
43. git fetch Download objects and refs from another repository.
44. git pull Fetch from and integrate with another repository or a local branch.
45. git push Update remote refs along with associated objects.
46. git command ——help Shows what the command can do and options for the command.
47. git help -g Lists various resources included in git that can be used to learn git. e.g. git help tutorial, git help workflow, etc.
48. git help tutorial Provides a tutorial for starting with Git.
49. Tools!
50. Command Line Interfaces can be scary • Eventually you’ll probably need to use Git from the command line. • When starting, a GUI can make using Git a lot more comfortable.
51. Git GUIs GitHub Desktop + Free & Open Source - Only works with GitHub GitKraken + Supports Linux - Only Free for non-commercial uses SourceTree + Most “powerful” of the three - Free, but not open source
52. Git Platforms
53. GitLab + Free private projects with most features + Free & Open Source + Literally perfect with no downsides whatsoever GitHub + Most popular of the three + Free public projects - Closed source Bitbucket + Free for up to 5 people per project - Closed source
54. Why learn to use Git? • Your eventual employer will almost definitely use it. • Great for group projects if everyone knows how to use it. • Keeps a backup of your project • You can go back to previous commits.
55. Resources • git-scm.com • ohshitgit.com • git help, git help -g
56. Q&A Questions about…. • Git • GitLab • Version control • etc.