Git inter-snapshot public
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This document summarizes key concepts of Git including snapshots, histories as sequences of snapshots, parallel universes/histories, and basic Git commands like init, add, commit, branch, checkout, merge, rebase, remote repositories, and free hosting services. The document uses diagrams and examples to explain how Git conceptually implements versions as snapshots and allows managing parallel software histories through branches.
Git inter-snapshot public
- 1. GIT: Inter-Snapshot SeongJae Park <sj38.park@gmail.com>
- 2. This Speak Aims To... Understanding conceptual inside of git Grow up a little once again together
- 3. Software Is Alive: Keeps Changing
- 4. Life Of Files FileA ver 0 FileB ver 0
- 5. Life Of Files FileB Changed FileA ver 0 FileB ver 1
- 6. Life Of Files FileA Changed FileB ver 1 FileA ver 1
- 7. Life Of Files FileB Changed Again FileA ver 1 FileB ver 2
- 8. Life Of Files “I miss FileA ver 0!” “Build fail, why? from when?” FileA ver 1 FileB ver 2
- 9. Software Is Alive: Keeps Changing “How To Keep Software’s Moment?”
- 10. Software Is Alive: Keeps Changing “How To Keep Software’s Moment?” $ ls 0213_1st.tar 0239_2nd.tar.gzip 0305_final.zip 0307_final2.alz
- 11. Software Is Alive: Keeps Changing “How To Keep Software’s Moment?” $ ls 0213_1st.tar 0239_2nd.tar.gzip 0305_final.zip 0307_final2.alz We will find a version. We always have. http://nofilmschool.com/sites/default/files/styles/article_wide/public/interstellar.jpg?itok=PDUgBX9v
- 12. VCS: Version Control System Help software history managing Just remember, You SHOULD use it
- 13. CVCS vs DVCS Centralized vs Distributed Not detail for this time(not main focus)… Just remember, CVCS is EVIL
- 14. git Distributed Version Control System Developed For Kernel SCM By Linus Torvalds “Only wimps use tape backup: real men just upload their important stuff on ftp, and let the rest of the world mirror it ;)” - Linus Torvalds Just remember, cool programmer uses GIT
- 15. TL; DR Snapshot is a moment of the universe History is a sequence of snapshots Parallel universes exist http://i0.kym-cdn.com/photos/images/newsfeed/000/021/503/tldr_trollcat.jpg?1318992465
- 16. GIT: BASIC CONCEPT History is a Sequence of Snapshots
- 17. Snapshot A moment of the universe $ tar cf snapshot.tar ShinyProject/* http://imageserver.moviepilot.com/simpsons-couch-the-simpsons-futurama-crossover-s-couch-gag-gets-weird.png?width=2213&height=1660
- 18. History: a Sequence Of Snapshots $ ls snapshots/ ss.1.tar ss.2.tar ss.3.tar ss.4.tar ss.5.tar http://vintageprintable.swivelchairmedia.com/wp-content/uploads/2011/05/Animal-Stop-motion-Cat-Running-Stop-motion-780x395.jpg a history
- 19. Parallel Universes Well known theory ;) For detail, http://www.youtube.com/watch?v=Ywn2Lz5zmYg
- 20. Parallel Universes In short, a snapshot could have multiple parents/children Parallel histories
- 21. GIT: CONCEPT, IN DETAIL Conceptual Implementation
- 22. Working, Staging, Snapshot Dirs ● Based on the snapshot concept, ○ VCS could be implemented using 3 types of directories ■ Working, Staging, Snapshot http://www.make-upstudio.com/files/images/trainingcenter/Large/LIndia-1-6.jpg http://studio.maginei.com/studioimages/studio.jpg http://venturebeat.com/wp-content/uploads/2012/05/snapshots.jpg
- 23. Working Directory Sandbox for your funny work, hack, anything Source code usually reside here http://www.make-upstudio.com/files/images/trainingcenter/Large/LIndia-1-6.jpg
- 24. Staging Directory Files to be captured in next snapshot http://studio.maginei.com/studioimages/studio.jpg
- 25. Snapshot Directory Whole snapshots reside here Every snapshot could be identified uniquely http://venturebeat.com/wp-content/uploads/2012/05/snapshots.jpg
- 26. Simple Example $ mkdir tars; cd tars $ echo 80 > sense_of_humor $ cp sense_of_humor ../staging/ $ tar cf ../snapshots/1st ../staging/* $ echo 65 > sense_of_humor $ tar cf ../snapshots/2nd ../staging/* $ tar xf ../snapshots/1st ./ https://pbs.twimg.com/media/B2W_L20CcAAtfGW.jpg:large
- 27. GIT: COMMANDS Conceptual Implementation of Commands
- 28. git init Create internal directories $ mkdir ./.git $ mkdir ./.git/snapshots $ mkdir ./.git/staging
- 29. git add <file path> Add files to staging directory $ cp <file path> ./.git/staging/
- 30. git commit Create a snapshot from staging dir $ tar cf ./git/snapshots/<unique id> ./git/staging/*
- 31. Branch Pointer to latest snapshot of a history branch ‘master’
- 32. Branch Pointer to latest snapshot of a history Follows subsequent snapshots automatically branch ‘master’ branch ‘master’
- 33. git branch <name> Create a branch with <name> Created branch follows current history (Below code does not implement history following feature, though) $ ln -S ./git/snapshots/<name> ./git/snapshots/<id>
- 34. git checkout <id or branch> ● Restore a snapshot <id> or <branch> is pointing on working directory ● If <branch>, transit to the branch’s history ○ <branch> will follows subsequent snapshots $ tar xf ./git/snapshots/<id> ./
- 35. GIT: PARALLEL HISTORIES There are parallel universes
- 36. Parallel Universes Well known theory ;) For detail, http://www.youtube.com/watch?v=Ywn2Lz5zmYg
- 37. Parallel Universes In short, a snapshot could have multiple parents/children Parallel histories
- 38. Parallel Universes In short, a snapshot could have multiple parents/children Parallel histories Parallel history 1
- 39. Parallel Universes In short, a snapshot could have multiple parents/children Parallel histories Parallel history 1 Parallel history 2
- 40. Parallel Universes In short, a snapshot could have multiple parents/children Parallel histories Parallel history 1 Parallel history 2 Parallel history 3
- 41. Parallel Universes Branch is useful to manage parallel histories branch ‘foo’ branch ‘master’
- 42. GIT: SCENARIOS It’s easy if you know parallel universes
- 43. “Wait, I did something wrong!” Past can’t be fixed(Available, actually… though not recommended) http://therecordingrevolution.com/wordpress/wp-content/uploads/2011/08/mistakes.gif
- 44. “Wait, I did something wrong!” Past can’t be fixed(Available, actually… though not recommended) Go back and start again from new parallel universe(no time-machine paradox!) http://d36xcvrkegf0f1.cloudfront.net/images/worlds/2755/HomerTimeTravels.jpg
- 45. Scenario: Horrible Thing Committed branch A
- 46. Scenario: Horrible Thing Committed Make new branch from last sane snapshot branch A branch B
- 47. Scenario: Horrible Thing Committed Do things right in this time branch B branch A
- 48. Scenario: Horrible Thing Committed Life goes on... branch B branch A
- 49. git merge <other branch> Create new child snapshot of Currently checked out(HEAD) snapshot and <other branch> branch B branch A (HEAD) $ git merge branch_Br
- 50. git merge <other branch> Create new child snapshot of Currently checked out(HEAD) snapshot and <other branch> branch A (HEAD) branch B $ git merge branch_Br $
- 51. Topic Branch New branch for every new topic coding branch topic1 branch topic2 branch master
- 52. Topic Branch New branch for every new topic coding New topic could be progressed parallel easily branch topic1 branch topic2 branch master
- 53. Topic Branch New branch for every new topic coding New topic could be progressed parallel easily It could be discarded or merged easily branch topic1 branch topic2 branch master
- 54. Topic Branch: Scenario 1. New feature required branch master
- 55. Topic Branch: Scenario 1. New feature required a. Create a topic branch branch topic1 branch master
- 56. Topic Branch: Scenario a. Create a topic branch and work on it branch topic1 1. New feature required branch master
- 57. Topic Branch: Scenario 1. New feature required a. Create a topic branch and work on it 2. Critical bug found a. Create a topic branch branch topic2 branch topic1 branch master
- 58. Topic Branch: Scenario 1. New feature required a. Create a topic branch and work on it 2. Critical bug found a. Create a topic branch and work on it branch topic1 branch topic2 branch master
- 59. Topic Branch: Scenario 1. New feature required a. Create a topic branch and work on it 2. Critical bug found a. Create a topic branch and work on it 3. Merge finished branch branch topic1 branch topic2 branch master
- 60. git rebase --onto <new base> <from> <to> Apply changes from <from> to <to> on <new base> and checkout applied snapshot a b c d e f branch “from” g h branch “to” branch “new_base”
- 61. git rebase --onto <new base> <from> <to> Apply changes from <from> to <to> on <new base> and checkout applied snapshot a b c d e f g h branch “to” branch “new_base” branch “from” h’
- 62. GIT: REMOTE Inter-stellar git repositories
- 63. Remote Repository ● Just Other’s snapshots directory ● It could be connected via ○ file system ○ http protocol ○ https protocol ○ ssh protocol ○ git protocol
- 64. git clone <remote repo path> Just fetch <remote repo> and checkout master branch of it The <remote repo> be named as ‘origin’ by default
- 65. git fetch <remote> Fetch <remote>’s snapshots to local repo <remote> is ‘origin’ by default cp <remote>/.git/snapshots/* ./git/snapshots/
- 66. git pull Just git fetch && git merge
- 67. git push <remote> <branch> Push <branch>’s snapshots to <remote>
- 68. Free GIT Repo Hosting Service ● GitHub ○ Popular service ○ Money for private repository ● Bitbucket ○ Popular, though less than GitHub ○ Free for restricted private repositories ● GitLab ○ GitHub like rich-features ○ Installable on your private machine ○ No limitation at all
- 69. Thank you :) http://jeancharpentier.files.wordpress.com/2012/02/capture-plein-c3a9cran-01022012-230955.jpg
- 70. This work by SeongJae Park is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http: //creativecommons.org/licenses/by-sa/3.0/.