GIT BASICS
by Ariejan de Vroom – Kabisa ICT
30th Juny 2009

WHAT THE GIT?!
“I'm an egotistical bastard, and I name all my projects after
myself. First Linux, now git.” – Linus Torvalds

GET GIT!
http://git-scm.com/

SURVEY
• Who is NOT using version control?
• SubVersion?
• Anything else?

WHY GIT?!
• Distributed Repositories
• Non-linear Development
• Very fast branching and merging
• Toolkit Design
• Scales
• Cryptographic authentication of history.

LET’S ROCK!
~/gitbasics $ git init
Initialized empty Git repository
in /Users/ariejan/gitbasics/.git/

LET’S ROLL!
~/gitbasics $ git clone
git@github.com/ariejan/gitbasics.git

~/gitbasics $ echo "Live long and prosper" > README
~/gitbasics $ git add README
~/gitbasics $ git commit -m "Added README"
[master (root-commit)]: created 8e60b09: "Added README"
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 README

WHAT JUST HAPPENED?
~/gitbasics $ git log
commit 8e60b09d3082e9473944075cc01b3b67bb97d5c3
Author: Ariejan de Vroom <ariejan@ariejan.net>
Date: Mon May 11 21:51:24 2009 +0200
Added README

HOW GIT WORKS
Working Directory
git add
Staging Area
git commit
Repository

WORKFLOW
• Hack! ( TextMate, vim, ... )
• Stage your changes ( git add )
• Review your changes ( git status | diff )
• Commit (locally) ( git commit )
• Repeat

USING BRANCHES
• Very, very fast
• Keep different code paths separate
• Try new things
• Atomic merges!

SURVEY
• How many of you use branching?
• Do you work exclusively on trunk/master?
• NEVER work on trunk/master?

BRANCHING
c1 c2 c3 c4
c5 c6

LET’S BRANCH!
~/gitbasics $ git checkout -b new_feature
Switched to a new branch "new_feature"
~/gitbasics $ git branch
master
* new_feature
~/gitbasics $ git checkout master
Switched to branch "master"
~/gitbasics $ git branch -d feature3
Deleted branch feature3

MERGING
• Merge two branches together
• Add new features
• Add bugs fixes

MERGING
c1 c2 c3 c4 c7
c5 c6

MERGING
~/gitbasics $ git checkout master
Switched to branch "master"
~/gitbasics $ git merge new_feature

REBASING
• Bring a branch up-to-date
• Rebasing is rewriting history!
• Don’t use rebasing on a branch you’re
sharing!

REBASING
c1 c2 c3 c4
c3’ c4’ c5 c6

REBASING
~/gitbasics $ git checkout new_feature
Switched to branch "new_feature"
~/gitbasics $ git rebase master

REMOTE
• Store and share your code!
• github.com
• gitosis ( self-managed over SSH )

PUSH
~/gitbasics $ git add origin git@github.com/ariejan/
gitbasics.git
~/gitbasics $ git push origin master

FETCH / PULL
~/gitbasics $ git fetch origin
~/gitbasics $ git pull origin master

WORKFLOW
Working Directory
add
Staging Area
commit checkout merge
Repository
push fetch pull
Remote

TAGGING
• Mark a point in history
• Optionally sign it cryptographically with
GnuPG

TAGGING
v1.0
c1 c2 c3 c4

TAGGING
~/gitbasics $ git tag -a -m "Tag v1.0" v1.0
Switched to branch "new_feature"
~/gitbasics $ git tag
v1.0
~/gitbasics $ git push --tags

THE STASH
• Stash away uncommited changes
• Ideal for quick bug fixes!

THE STASH
~/gitbasics $ git status
# modified: README
~/gitbasics $ git stash
~/gitbasics $ git status
nothing to commit
# Hack, stage, review, commit, etc.
~/gitbasics $ git stash pop
~/gitbasics $ git status
# modified: README

CONFLICTS
• Conflicts happen
• Git is clever
• Easy to resolve manually
• Merges are atomic!

CONFLICTS
~/gitbasics $ git merge awesome_feature
Auto-merged README
CONFLICT (content): Merge conflict in README
Automatic merge failed; fix conflicts and
then commit the result.
~/gitbasics $ vim README
~/gitbasics $ git add README
~/gitbasics $ git commit -m “fixed merge
conflict”

GIT-SVN
It’s like being the Chuck Norris of the team!

ASSUME THIS
~/gitbasics $ svn log http://svnhub.com/project/trunk
------------------------------------------------------
r17048 | ariejan | 2009-06-30 ....
Updated README.
SVN Repository courtesy of SVNHub.com

CHECKOUT
~ $ mkdir gitbasics
~ $ cd gitbasics
~/gitbasics $ git-svn init http://svnhub.com/project/
trunk
~/gitbasics $ git-svn fetch -r17048
A README

UPDATE
~/gitbasics $ git-svn rebase

COMMIT
~/gitbasics $ git-svn dcommit

WORKFLOW
~/gitbasics $ git-svn init URL
~/gitbasics $ git-svn rebase && git-svn fetch
~/gitbasics $ git checkout -b new_feature
~/gitbasics $ git add && git commit
~/gitbasics $ git checkout master
~/gitbasics $ git-svn rebase
~/gitbasics $ git merge new_feature
~/gitbasics $ git-svn dcommit

SURVEY
• Who is going to try Git?
• Stick with SubVersion?
• Try git-svn?

THANKS!
Slides will be published at http://slideshare.net/ariejan
Contact me at ariejan@kabisa.nl