Your SlideShare is downloading. ×
Smalltalk on Git
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.

Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Smalltalk on Git


Published on

An introduction on using git and git-svn.

An introduction on using git and git-svn.

Published in: Technology
1 Comment
  • Fioricet is often prescribed for tension headaches caused by contractions of the muscles in the neck and shoulder area. Buy now from and make a deal for you.
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

No notes for slide


  • 1. Git in a Nutshell Sort of... Mathias Meyer Ruby User Group Berlin
  • 2. What the git? • Git is not the next Subversion • Git is a content tracker • Git is almost a versioned file system • Git is distributed
  • 3. What the git? • Git is a huge collection of commands • Git is f***ing fast
  • 4. Ancient History • Developed to replace BitKeeper for the Linux kernel development • Started out as a couple of scripts built by Linus Torvalds • Used by Rails, Merb, Ubuntu,, Wine, Rubinius and Linux (whoa!) • Started out focused on development with a central maintainer
  • 5. Basics • Every working copy is a full-fledged repository • Git only tracks content • Content is identified by a hash • Though that content has a name • The same content is only stored once
  • 6. Basics • Everything is stored in one .git directory in the top level of your working copy • Git uses an index to find changes in the working directory • The index is a snapshot of a specific tree in the repository
  • 7. Git Objects • Git knows four types of objects • Have SHA1 IDs • Can be addressed with the six first bytes of the hash • Are compressed with gzip
  • 8. Commits • Refers to a tree and usually a parent commit (usually the commit before the current one) • Can have two or more parents, then they represent a merge • Or no parent at all • Stored with a log message
  • 9. Tree • A simple structure containing names of blobs and other trees • Represents a snapshot of the source tree
  • 10. Blob • Contains data, e.g. file content • Blobs don’t have names • Their names are derived from the tree • Will be found through associations from trees and commits
  • 11. Tag • Glued to a specific object • Marks a specific point in the Git timeline with a name
  • 12. HEAD branch commit tree tree blob tree blob blob
  • 13. Git Branches • master - default development branch • origin - default upstream branch • HEAD - current branch
  • 14. Git Branches • HEAD~2, master^1, wtf? • ~N references the Nth generation grandparent of a commit • ^N references the Nth parent of a commit, only useful for merges of two or more commits • So....
  • 15. Git Branches • HEAD~2 is the second generation grand- parent of the last commit on the current branch • master^2 is the second parent of the last commit on master • master~2^2 is the second parent of the second generation grand-parent of the last commit on the current branch
  • 16. Git Branches Rrright.
  • 17. Git Branches • Branches are cheap and easy • A branch is an ID pointing to a tree and a parent commit • Merging is cheap, fast and almost painless • Ergo: Branching in Git rocks
  • 18. How Do I Get Git? • MacPorts (port install git-core +svn) • Git Installer for Leopard • On every Linux distribution (apt-get|rpm install git-core) • On Windows? I think so
  • 19. How Do I Get Started? • mkdir project.git • cd project.git • git init • Start hacking
  • 20. How Do I Get Started? • Or go to GitHub • Best GUI for Git evah
  • 21. Everyday Git • Some of the commonly used Git commands • Called the Porcelain
  • 22. Set up camp • git config --global “Mathias Meyer” • git config --global “”
  • 23. git clone • Creates a local working copy of a remote project • git clone git:// macistrano.git
  • 24. git checkout • Checks out code from a branch • Will overwrite your local changes • git checkout -b will create a branch and check it out
  • 25. git branch • Shows, creates and deletes branches • git branch master * show_me_the_money • git branch new_branch • git branch -d new_branch
  • 26. git fetch • Fetches all objects from a remote repository which are not in the local repository
  • 27. git add • Schedule changes in one or more files for the next commit
  • 28. git rm • Removes files
  • 29. git mv • Moves files and directories around
  • 30. git commit • Isn’t it obvious? • It will check in your changes • But only the ones you added • Use git commit -a to check in all the changes without adding them • git commit <file> will commit the file without the need to add it
  • 31. git status • Shows staged and unstaged changes • staged = added • unstaged = new, conflicts, changed
  • 32. git push • Pushes your changes to a remote repository • git push origin pushes the current branch • git push origin master pushes the master branch
  • 33. git pull • Different way to do a merge • git pull = git fetch + git merge
  • 34. git log • Shows the commit history • Can be verbose if you want it to
  • 35. git merge • Merges the changes from a branch into your current branch • git merge rails_2_1 • And that’s that • In case of conflicts, these need to be resolved and then committed
  • 36. git tag • Duh! • Associates a tag with the
  • 37. git stash • It’s like a clipboard in your repository • Need to work on something else but don’t want to commit your local changes yet? • git stash save will save all your changes • git stash apply will reapply them after you’re done • git stash list shows all the stashes • git stash show shows the changes of a stash
  • 38. git show • Shows the details of a specified, or the last commit
  • 39. git archive • Creates an export of your repository • Default is tar • Convenient, no? • git archive release_2_1 > release_2_1.tar
  • 40. git .... • There’s lots more • Which you probably won’t need most of the time • You use 20 or so for everyday work • Some of them only on special occasions • git-<tab> and start digging
  • 41. Git-Svn • The gateway drug for Subversion users • Warning:You don’t want to use the svn command ever again • Ever!
  • 42. Git-Svn • Basically a couple of Perl scripts • Using the Subversion bindings • Translates Subversion commits to Git commits and vice versa
  • 43. Show me how! • mkdir webistrano • git svn init -s webistrano • git svn fetch • Get a coffee...
  • 44. Everyday Git-Svn • git checkout -b make_me_rich • ...endless hours of coding... • ...and writing tests... • git add lib/monetize.rb spec/monetize_spec.rb • git commit
  • 45. Everyday Git-Svn - Merging • git commit -a • git checkout master • git svn rebase • git merge make_me_rich • tests... • git svn dcommit • git branch -d make_me_rich
  • 46. Everyday Git-Svn - Merging • The potentiel downside of using git merge: • git svn dcommit will check in all the commits from the branch in one single svn commit
  • 47. Everyday Git-Svn - Merging • The alternative • dcommit from the branch • rebase the changes on master
  • 48. Everyday Git-Svn - Merging • git commit -a • git svn rebase # on branch make_me_rich • git svn dcommit # on branch make_me_rich • git checkout master • git svn rebase • git branch -d make_me_rich
  • 49. Some Git Awesomeness • Find out what commits will be ci’d to svn • git svn dcommit -n (rather sparse) • git cherry -v trunk (full glory) • Commit partial changes of a file • git add --patch
  • 50. But I don’t like the CLI • Use git gui for a “nicer” interface • Use Gitk to visualize commits and branches • For both: brace yourself to be blinded • Much nicer, less powerful: GitNub • TextMate bundle!
  • 51. In the end... • Git will blow your brains out • In several ways • It takes a while to get used to it • But it’s totally worth it • Even if you’re still using Subversion as a central repository
  • 52. The Bad Stuff • Poor documentation, be prepared to spend some time on Google • Complex beast, lots of small commands • No API
  • 53. Resources • Git Home ( • Git User’s Manual ( software/scm/git/docs/user-manual.html) • Git PeepCode ( git) • Must-read: Git Internals ( products/git-internals-pdf) • GitCasts (