Git

Intro to Git presentation. Presented in ATLRUG in 2008.

Transcript

2. jnewland.com/tag/git
3. What is Git? • A popular distributed version control system designed to handle very large projects with speed and efficiency. • http://git.or.cz/
4. quick survey • Who is not using source control? • SVN? • CVS? (still?)
5. • Written by Linus Torvalds • Written to manage the Linux Kernel Git History
6. Getting Git
7. For the brave # install gnupg, gettext $ curl -O http://kernel.org/pub/software/scm/git/ git-1.5.4.1.tar.gz $ tar xzf git-1.5.4.1.tar.gz $ ./configure $ make $ sudo make install $ curl http://www.kernel.org/pub/software/scm/git/git- manpages-1.5.4.tar.bz2 $ sudo tar xjf git-manpages-1.5.4.tar.bz2 -C /usr/ local/share/man
8. For the weak sudo port install git-core +svn sudo apt-get install git-core sudo yum install git-core
9. Initial Setup $ git config --global user.name='My Name' $ git config --global user.email=me@mydomain.net # optional, for pretty colors $ git config --global color.diff=auto $ git config --global color.diff.new=cyan $ git config --global color.diff.old=magenta $ git config --global color.diff.frag=yellow $ git config --global color.diff.meta=green $ git config --global color.diff.commit=normal
10. Why Git? • Distributed, not Centralized • Revolutionizes how you use branching • Extremely stupidly ridiculously fast, even with large projects • Community
11. Centralized vs Distributed
12. Centralized VCS • Repository • History stored in central location • Checkout • A ‘working tree’
13. Distributed VCS • Every Git working directory is a full-fledged repository with full revision tracking capabilities, not dependent on network access or a central server. • Commits happen offline. • Commits can then be pushed and pulled between repositories with shared history.
14. Wait, commits happen offline?
15. Commits happen offline!!!!!!!11!!!
16. on the plane
17. on the train
18. at that crappy coffee shop with the paid WiFi
19. at an ATLRUG meeting
20. Branching FTW
21. “But I don’t branch”
22. because you don’t use Git
23. quick survey #2 • How many of you use branching? • Work exclusively on trunk/master? • NEVER work on trunk/master?
24. Why branching with Git is awesome • Instant $ time git checkout -b newbranch Switched to a new branch "newbranch" real 0m0.227s • Private • Merging doesn’t suck
25. Forget about ‘breaking the build’ • ‘Atomic’ commits are a thing of the past • ‘Atomic’ merges
26. • Prototype well-developed changes • Commit early and often • Review and revise before you merge Topic Branches
27. With Git, branches are now a part of my everyday workflow
28. ‘Tomorrow’ branch
29. ‘Drunk’ branch
30. Performance
31. Offline Operations • Performing a diff • Viewing file history • Committing changes • Merging branches • Obtaining any other revision of a file • Switching branches
32. Online operations are fast too $ time svn co http://svn.rubyonrails.org/rails/ trunk/ ... real 0m29.537s
33. Online operations are fast too $ time git clone --depth 1 git://github.com/josh/ rails.git ... real 0m9.088s
34. Online operations are fast too $ time git clone git://github.com/josh/rails.git ... real 0m37.512s
35. Git for Subversion Users
36. This looks familiar $ git status $ git log $ git blame $ git add FILE $ git rm FILE $ git mv FILE $ svn status $ svn log $ svn blame $ git add FILE $ git rm FILE $ git mv FILE
37. Creating a Repo $ pwd ~/src/foo $ git init $ git add . $ git commit
38. Checking out a Repo $ git clone REPO_URL
39. git status • Untracked Files • Brand new file • Changed but not updated • Locally changed file not in the index • Changes to be committed • ‘The Index’
40. The Index • Staging area for your next commit • Sort of like files marked A, M, D in svn status output
41. One major difference • After making any changes to the working directory, and before running the commit command, you must use the add command to add any new or modified files to the index.
42. Example # create bar and to the index echo “foo” > bar git add bar # change bar, and thus remove from the index echo “ “ >> bar # add bar to the index again git add bar
43. Committing • git commit • commit what’s in the index • git commit -a • adds changed but not untracked files to the index, then commits • exactly like SVN
44. Diffs # diff between working tree and the index $ git diff # diff between the index and last commit $ git diff --cached # diff between working tree and last commit $ git diff HEAD
45. Logs # just like svn $ git log # find a commit changed a specific string $ git log -S"def stupid_method" # log with patches for each commit $ git log -p
46. Reverting Changes $ git checkout PATH $ svn revert PATH
47. git revert != svn revert # most similar to svn revert $ git checkout . # reverse commit <rev> and commit the result $ git revert <rev>
48. Branching # create a new branch $ git branch NEW_BRANCH # switch to this branch $ git checkout NEW_BRANCH # create a new branch and check it out in one step $ git checkout -b NEW_BRANCH
49. More Branching # view available branches $ git branch * new_branch master # delete a branch $ git branch -d ALREADY_MERGED_BRANCH $ git branch -D BAD_BRANCH
50. Diffing and Logging with Branches # log of changes to other_branch not in master $ git log NEW_BRANCH..master # diff of those changes $ git diff NEW_BRANCH..master
51. Merging # get back to the master $ git checkout master # merge in changes from your other branch $ git merge NEW_BRANCH # optionally, delete the branch $ git branch -d NEW_BRANCH
52. Rebasing # store local changes not in BRANCH_NAME as patches, updates the local branch to BRANCH_NAME, then applies the patches $ git rebase BRANCH_NAME
53. Danger, Will Robinson • Rebase is dangerous • Rewrites commit history • Don’t use on a branch you’re sharing
54. Oh noes! Merge Conflicts!
55. Easy Conflict Resolution $ git merge conflict_branch Auto-merged README CONFLICT (content): Merge conflict in README Automatic merge failed; fix conflicts and then commit the result. # fix conflict then commit $ vim README $ git add README $ git commit -m “fixed merge conflict”
56. Collaboration with GIT
57. Hosting a Git Repo • git-daemon • gitosis
58. Hosting a Git Repo • git-daemon • gitosis
59. github.com
60. Fork your friends
61. ‘MySpace for hackers’
62. Track forks of your repository
63. Free for public repos
64. • Still in beta • Email me at jnewland@gmail.com if you’d like an invite (20 left)
65. Common Use Cases • Contributor • Create Patches • Send Patches • Maintainer • Review Patches • Apply Patches
66. Contributor
67. Fork, then clone • Fork repo at github http://github.com/jnewland/atlrug-demo/tree/master • Clone your copy of my repo $ git clone git@github.com/USERNAME/atlrug-demo.git
68. Make changes $ git checkout -b my_branch $ echo “hello again” >> README $ git commit -a
69. Track the upstream # add a remote $ git remote add jnewland git://github.com/ jnewland/atlrug-demo.git # add a branch $ git checkout -b jnewland/master # update the tracking branch $ git pull jnewland master
70. Merge it all together # switch back to the master $ git checkout master # update master with your changes $ git merge my_branch # update master with upstream changes $ git merge jnewland/master
71. Push it real good $ git push origin master
72. Sending Patches • Old skool: $ git format-patch jnewland • New hotness - ‘Pull Request’
73. No more emailing patches
74. No more emailing patches
75. Maintainer
76. Receive pull request
77. Grab mtodd’s changes # add a remote $ git remote add mtodd git://github.com/mtodd/ atlrug-demo.git # add a branch $ git checkout -b mtodd/master # pull the changes $ git pull mtodd master
78. Merge, then push! # switch back to master $ git checkout master # merge $ git merge mtodd/master # push $ git push
79. SVN Integration
80. “the best part about GIT is that no one has to know you’re using it”
81. basic git-svn workflow $ git svn clone REPO_URL # ... hack hack hack ... $ git commit -a # ... hack hack hack ... $ git commit -a $ git svn rebase $ git svn dcommit
82. better workflow $ git svn clone REPO_URL $ git checkout -b new_branch # ... hack hack hack ... $ git commit -a $ git svn rebase $ git svn dcommit $ git checkout master $ git branch -d new_branch $ git svn rebase
83. Pretty GUIs
84. gitk • Bundled with git • Excellent visualization of branching history
85. GitNub • http://github.com/Caged/ gitnub/tree/master • RubyCocoa
86. More Resources • http://git.or.cz/ • http://cheat.errtheblog.com/s/git/ • http://github.com/guides • #git and #github on irc.freenode.org
87. Questions? Comments? Flames?
88. Jesse Newland jnewland@gmail.com http://jnewland.com
89. flickr is awesome • http://flickr.com/photos/alper/528441936/ • http://flickr.com/photos/joan-fabregat/ 1947832858/ • http://flickr.com/photos/feria/2316579746/