Git Version Control System: How to Use, Install, and Manage Repositories

1. Git A distributed version control system Powerpoint credited to University of PA And modified by Pepper

2. Version control systems • Version control (or revision control, or source control) is all about managing multiple versions of documents, programs, web sites, etc. • Almost all “real” projects use some kind of version control • Essential for team projects, but also very useful for individual projects • Some well-known version control systems are CVS, Subversion, Mercurial, and Git • CVS and Subversion use a “central” repository; users “check out” files, work on them, and “check them in” • Mercurial and Git treat all repositories as equal • Distributed systems like Mercurial and Git are newer and are gradually replacing centralized systems like CVS and Subversion

3. Why version control? • For working by yourself: • Gives you a “time machine” for going back to earlier versions • Gives you great support for different versions (standalone, web app, etc.) of the same basic project • For working with others: • Greatly simplifies concurrent work, merging changes • For getting an internship or job: • Any company with a clue uses some kind of version control • Companies without a clue are bad places to work

4. Download and install Git • Tutorials • Standard one: http://git-scm.com/downloads • Here’s one from StackExchange:http://stackoverflow.com/questions/315911/git-for-beginners-the-definitive-practical-guide#323764 • Install Git on your machine from http://git-scm.com/downloads • Accept context menu items • Git access: • Right click from windows explorer • gitBash to enter commands • Current local directory is folder you launched from • Good idea - one folder for your git local access

5. Introduce yourself to Git • Start git / gitBash • See your options: • git config -l • Enter these lines (with appropriate changes): • git config --global user.name "John Smith" • git config --global user.email jsmith@seas.upenn.edu • You only need to do this once • If you want to use a different name/email address for a particular project, you can change it for just that project • cd to the project directory • Use the above commands, but leave out the --global

6. Setting options • When you “commit,” git will require you to type in a commit message • For longer commit messages, you will use an editor • To change the default editor: • git config --global core.editor /usr/bin/vim • You may also want to turn on colors: • git config --global color.ui auto • See your options: • git config -l

7. Clone repositories on panther • Our repositories • http://home.adelphi.edu/~pe16132/csc440/repositories.html • Get the files from your repository before starting • Make a local respository as a clone of master • Make a new folder • Right click the folder and choose git bash • Type: git clone ssh://pepper@panther.adelphi.edu/opt/git/csc480ASpring15.git • Enter your ecampus password • See all the contents of the folder • Windows Explorer: Change folder and search options to show hidden files, folders and drives • Git Bash (unix) : ls -a to see the .git folder.

8. Using Gui to Clone repository • Open git Gui • Choose Clone Existing Repository • Source: ssh://pepper@panther.adelphi.edu/opt/git/csc480ASpring15.git • Target: New folder on your system • Enter password 3 times

9. GitBash Changing your repositories • Make changes • See what changed • git diff • Stage changes • git add –all (or particular files) note 2 dashes! • git diff –cached (:q! to exit) • Still only in your repository • Put changes back up into repository • Commit your staged changes in your repository • git commit -m "the reason for the change" • Update the respository: • git push origin

10. GitGui Managing your Repositories • Rescan to see changes to stage • Stage changed to say you want to track those changes • Click left box to unstage • Sign off to start a commit message text • Commit - Enter reason first • Push the changes up to the repository

11. Viewing and Resetting repository • See what is on the repository • git remote • ls to see files • cd & cd .. to move around folders • cat to see file contents • vi to edit file contents and end with <esc> :wq • Get what is on repository • git pull • If it says to resolve manually, just vi that file and see the head which is yours

12. Failed Push • When you don't have the latest copy it will fail:

13. Recover from failed push • Copy your repository elsewhere first just in case • Use git bash • Git pull to pull down the changes • Files needing merging will have both sets of text : <<<<<<< HEAD change once not pushed ======= change once pushed >>>>>>> d43e1181ce3d7d0ca45fe0d2ce1a6120def02c37 • Head is your local copy version • Add --all ; commit and push again

14. Typical workflow • git pull remote_repository • Get changes from a remote repository and merge them into your own repository • git status • See what Git thinks is going on • Use this frequently! • Work on your files • git add –-all (or just changes) • git commit –m “What I did” • git push

15. Helpful gitBash commands • Show staged differences: git diff -- cached • Show status : git status • Show branches: git branch • See history: git log • Checkout a branch: git checkout branch • Fetch so you can look but maybe not take: git fetch • Pull will fetch and merge with what you have: git merge

16. Git log commands • git log • --pretty=oneline --max-count=2 git log • --pretty=oneline --since='5 minutes ago' git log • --pretty=oneline --until='5 minutes ago' git log • --pretty=oneline --author=<your name> git log • --pretty=oneline –all

17. Git log pretty • git log --pretty=format:"%h %ad | %s%d [%an]" --graph --date=short • --pretty="..." defines the output format. • %h is the abbreviated hash of the commit • %d commit decorations (e.g. branch heads or tags) • %ad is the commit date • %s is the comment • %an is the name of the author • --graph tells git to display the commit tree in the form of an ASCII graph layout • --date=short keeps the date format short and nice

18. Good aliases • alias gs='git status ' • alias ga='git add ' • alias gb='git branch ' • alias gc='git commit' • alias gd='git diff' • alias go='git checkout ' • alias gk='gitk --all&' • alias gx='gitx --all' • alias got='git ' • alias get='git '