git notes

1. Git
A distributed version control system
Powerpoint credited to University of PA
And modified by Pepper
31-Jul-23

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
2

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
3

4. Download and install Git
 There are online materials that are better than any that I could
provide
 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
4

5. Introduce yourself to Git
 Start git / gitBash
 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
5

6. Choose an editor
 When you “commit,” git will require you to type in a
commit message
 For longer commit messages, you will use an editor
 The default editor is probably vim
 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
6

7. Your repositories
 We have created 6 class repositories on panther, and
here are their paths.

ssh://user_name@panther.adelphi.edu/opt/git/csc271books.git

ssh://user_name@panther.adelphi.edu/opt/git/csc271tv.git

ssh://user_name@panther.adelphi.edu/opt/git/csc271store.git

ssh://user_name@panther.adelphi.edu/opt/git/csc271movies1.git

ssh://user_name@panther.adelphi.edu/opt/git/csc271games1.git

ssh://user_name@panther.adelphi.edu/opt/git/csc271movies2.git

Prior class: csc440Spring14r1

Use instructions to follow
7

8. Using your repositories on panther
 Get the files from your repository before starting
 Make a local respository as a clone of master
 git clone /opt/git/csc271books
 See all the contents of the folder
 ls -a to see the .git folder.
 Make changes
 See what changed
 git diff
 Stage changes
 git add –all (or particular files)
 git diff –cached
 Still only in your repository
8

9. Using 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
 See what is on the repository
 git remote
 Get what is on repository
 git pull
 If it says to resolve manually, just vi that file and see the head
which is yours
9

10. 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
10

11. 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
11

12. 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
12

13. 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
13

14. 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 '
14