This document discusses version control systems and provides information about Git. It begins with an overview of version control and some common systems like CVS, Subversion, Mercurial and Git. It then covers the basics of local and centralized version control systems. The advantages of distributed version control systems like Git are explained. The document outlines some key advantages and disadvantages of Git. Finally, it provides instructions for basic Git operations like initializing a repository, making commits, cloning repositories and typical workflow steps.

2. Content
 Version control
 Advantages & disadvantages of GIT
 GIT basics
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3. Version Control
 Version control (or revision control, or source control) is all
about managing multiple versions of documents,
programs, web sites, etc.
 Some well-known version control systems are CVS, Subversion,
Mercurial, and Git.
 Distributed systems like Mercurial and Git are newer and are
gradually replacing centralized systems like
CVS and Subversion.
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4. Local Version Control
 Local version-control method of choice is to copy files into
another directory(perhaps a time-stamped directory, if they’re
clever).
 This approach is very common because it is so simple, but
it is also incredibly error prone.
 Ex :-
• RCS
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5. Local Version Control5

6. Centralized Version Control
 Traditional version control system.
• Server with database
• Clients have a working version
 Challenges
• Multi-developer conflicts
• Client/server communication
 Ex :-
• CVS
• Subversion
• Visual source safe
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7. Centralized Version Control
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8. Distributed Version Control
 Authoritative server by convention only.
 Every working checkout is a repository.
 Get version control even when detached.
 Backups are trivial.
 Ex :-
• Mercurial
• BitKeeper
• Darcs
• Bazaar
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9. Distributed Version Control
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10. Advantages of GIT
 Resilience
• No one repository has more data than any other
 Speed
• Very fast operations compared to other VCS (I’m looking at
you CVS and Subversion)
 Space
• Compression can be done across repository not just per file
• Minimizes local size as well as push/pull data transfers
 Simplicity
• Object model is very simple
 Large user base with robust tools
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11. Disadvantages of GIT
 Definite learning curve, especially for those used to centralized
systems.
• Can sometimes seem overwhelming to learn
 Conceptual difference
 Huge amount of commends
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12. GIT Basics
 Storing data as changes to a base version of
each file.
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13.  Storing data as snapshots of the project over time.
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14.  Working directory, staging area, and Git directory.
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15. Introduce yourself to GIT
 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
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16. Create and fill a repository
 cd to the project directory you want to use.
 Type in git init
• This creates the repository (a directory named .git).
• You seldom (if ever) need to look inside this directory.
 Type in git add
• The period at the end is part of this command!
• Period means “this directory”.
• This adds all your current files to the repository.
 Type in git commit –m "Initial commit“
• You can use a different commit message, if you like.
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17. Clone a repository from elsewhere
 git clone URL
 git clone URL mypath
• These make an exact copy of the repository at the given URL.
 git clone git://github.com/rest_of_path/file.git
• Github is the most popular (free) public repository.
 All repositories are equal,
• But you can treat some particular repository (such as one on
Github) as the “master” directory.
 Typically, each team member works in his/her own repository,
and “merges” with other repositories as appropriate.
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18. Making commits
 If you create new files and/or folders, they are not tracked by Git
unless you ask it to do so.
• git add newFile1 newFolder1 newFolder2 newFile2
 Committing makes a “snapshot” of everything being tracked into
your repository.
• A message telling what you have done is required
• git commit –m “Uncrevulated the conundrum bar”
• git commit
 This version opens an editor for you the enter the message.
 To finish, save and quit the editor.
 Format of the commit message.
• One line containing the complete summary.
• If more than one line, the second line must be blank.
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19. 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 /path/to/editor
You may also want to turn on colors:
• git config --global color.ui auto
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20. 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 (remember to add any new ones).
 git commit –m “What I did”
 git push
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21. Multiple versions
Initial commit
Second commit
Third commit
Bob gets a copy
Fourth commit
Merge
Bob’s commit
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