Version Control
Systems
Understanding the differences between centralized and
decentralized version control systems and the options
of different types of VCS available

Has this ever
happened?
• You look in the trash for files.
• You have more than two or three levels of
undo in a document.
• You have emailed someone to send you a
copy of some files.
• FTP has died mid transfer leaving partial
files.

What is Version
Control
• Revision control (also known as version
control, source control or (source) code
management (SCM)) is the management of
changes to documents, programs, and other
information stored as computer files.*
*http://en.wikipedia.org/wiki/Revision_control

What is Version
Control
• Changes are usually identified by a number
or letter code, termed the "revision
number", "revision level", or simply
"revision".
*http://en.wikipedia.org/wiki/Revision_control

What is Version
Control
• Each revision is associated with a
timestamp and the person making the
change. Revisions can be compared,
restored, and with some types of files,
merged.
*http://en.wikipedia.org/wiki/Revision_control

Types of Version
Control
• Centralized
• CVS, Subversion, Perforce etc.
• Distributed
• GIT, Mercurial, Bazaar

Centralized
• Needs to be online or
LAN to repo.

Distributed
• Do not need to be
online. No central
Repo.

People Are Divided
• “Hey, you can use your old model if you want to. git
doesn't *force* you to change. But trust me, once
you start noticing how different groups can have
their own experimental branches, and can ask
people to test stuff that isn't ready for mainline yet,
you'll see what the big deal is all about.”
Centralized _works_. It's just *inferior*.
Linus Torvalds in a letter to the KDE team 20 Aug 2007

People Are Divided
• "Merging is the key to software developer
collaboration."
Mark Shuttleworth (Ubuntu / Canonical Ltd.):

People Are Divided
• "By 2011-2012, I predict this technology will be
widely adopted and many teams will wonder how
they once managed without it."
Ian Clatworthy (Canonical / Bazaar)

People Are Divided
• "Subversion has been
the most pointless
project ever started".
"If you like using CVS,
you should be in some
kind of mental
institution or
somewhere else".
Linus Torvalds

What else is there
• Mercurial (hg) and Bazaar (bzr) -
decentralized. File Revision System not
Delta Change Systems.
• CVS (dead), Perforce (ask kyle and fletcher)

GIT & SVN
Copy a Project
• > git clone url
> git pull
• > svn checkout url
> svn update

GIT & SVN
Create a Repository
• > git init
• > create repo

GIT & SVN
Add to First Repo
• > git add .
> git commit
• > svn import file://repo

GIT & SVN
Check Differences
• > git diff
• > svn diff | less

GIT & SVN
Check Status
• > git status
• > svn status

GIT & SVN
Restore from Revision
• > git checkout path
• > svn revert path

GIT & SVN
Moves and Changes
• > git add file
> git rm file
> git mv file
• > svn add file
> svn rm file
> svn mv file

GIT & SVN
Committing
• > git commit -a
• > svn commit

GIT & SVN
Reviewing History
• > git commit -a
• > svn commit

GIT & SVN
Tagging and Branching
• > git tag -a name
• > svn copy http://example.com/svn/trunk
http://example.com/svn/tags/name

GIT & SVN
Tagging and Branching
• > git tag -a name
• > svn copy http://example.com/svn/trunk
http://example.com/svn/tags/name

GIT & SVN
Tagging and Branching
• > git tag -l
> git show tag
• > svn list http://example.com/svn/tags/
> svn log --limit 1 http://example.com/svn/
tags/tag

GIT & SVN
Tagging and Branching
• > git branch branch
> git checkout branch
• > svn copy http://example.com/svn/trunk
http://example.com/svn/branches/branch
> svn switch http://example.com/svn/
branches/branch

GIT & SVN
Changing Branches
• > git merge branch
• > svn merge -r 20:HEAD http://
example.com/svn/branches/branch

GIT & SVN
Remote Branches
• > git clone url
• > svn checkout url

GIT & SVN
Remote Branches
• > git checkout --track -b branch origin/
branch
• > svn switch url

GIT & SVN
Cherry Picking
• > git cherry-pick rev
• > svn merge -c rev url

Git GUI
• gitc
• git-gui
• git cola
• gitx

More Information
• http://www.infoq.com/articles/dvcs-guide
• http://git.or.cz/course/svn.html