Git Introduction

This is slides for my ex-colleagues when I introduce git. Wish they to enjoy this wonderful tool.

Transcript

1. Git Introduction Julian Chu a.k.a. Walkingice
2. Who create Git • Linus Torvalds • Maintains Linux Kernel more than 20 yrs • “Just for hobby” • Android, Server, Embedded System
3. Git 1. For Linux Kernel 1. Thousands of developers in many countries 2. Thousands of branches 3. communicate via network 2. Fast 3. Is Open Source and For Open Source
4. What Problems to Solve 1. Many people works in one project 2. Many branches in one project 3. Many features in developing 4. How to share piece of code in different projects
5. How do we start? • From a simple program • Patch • Commit • Branch
6. Simple Program • Print Strings • Calcluate 1 + 2 + + 100
7. Step 1 # i n c l u d e < s t d i o . h > i n t m a i n ( ) { p r i n t f ( " h i \ n " ) ; r e t u r n 0 ; }
8. Step 2 # i n c l u d e < s t d i o . h > i n t m a i n ( ) { p r i n t f ( " f o o \ n " ) ; p r i n t f ( " b a r \ n " ) ; r e t u r n 0 ; }
9. Step 3 # i n c l u d e < s t d i o . h > s t a t i c v o i d p r i n t S t r s ( ) { p r i n t f ( " f o o \ n " ) ; p r i n t f ( " b a r \ n " ) ; } i n t m a i n ( ) { p r i n t S t r s ( ) ; r e t u r n 0 ; }
10. Step 4 # i n c l u d e < s t d i o . h > s t a t i c v o i d p r i n t S t r s ( ) { p r i n t f ( " f o o \ n " ) ; p r i n t f ( " b a r \ n " ) ; } s t a t i c v o i d c a l c ( ) { i n t i = 0 , t o t a l = 0 ; f o r ( i = 1 ; i < = 1 0 0 ; i + + ) { t o t a l = t o t a l + i ; } p r i n t f ( " t o t a l : % d \ n " , t o t a l ) ; } i n t m a i n ( ) { p r i n t S t r s ( ) ; c a l c ( ) ; r e t u r n 0 ; }
11. Step 5 # i n c l u d e < s t d i o . h > s t a t i c v o i d p r i n t S t r s ( ) { p r i n t f ( " f o o \ n " ) ; p r i n t f ( " b a r \ n " ) ; } s t a t i c v o i d c a l c ( ) { i n t b o t t o m = 1 , t o p = 1 0 0 ; p r i n t f ( " t o t a l : % d \ n " , ( b o t t o m + t o p ) * t o p / 2 ) ; } i n t m a i n ( ) { p r i n t S t r s ( ) ; c a l c ( ) ; r e t u r n 0 ; }
12. Progress • We develops our project in many steps. empty step 1 step 2 step 3 step 4 step 5
13. Patch Each steps create a patch. A patch is a snippet of modification that adds or removes lines from code. • patch / diff • Git is patch based tool • Git manages patches in order
14. Commits empty step1 step2 step3 step4 step5 Step1.patch Step2.patch Step3.patch Step4.patch Step5.patch
15. Commits(2) e09160 ede7ee ffabac 450e22 f17364 be6238 Step1.patch Step2.patch Step3.patch Step4.patch Step5.patch • Conceptually .. • commit 450e22 = commit ffabac + Step3.patch • commit ffabac = commit ede7ee + Step2.patch • We could regards each commits as ‘snapshot’
16. Git Internal Objects • Git Internal Objects • Git is more like File System • Git is a simple key-value data store
17. Summary for commits • Improve source code step by step • Each improvement is a Patch • Git manages patches in order • Each snapshot has a hash
18. .git directory . ├ ─ ─ . g i t │ ├ ─ ─ b r a n c h e s │ ├ ─ ─ C O M M I T _ E D I T M S G │ ├ ─ ─ c o n f i g │ ├ ─ ─ d e s c r i p t i o n │ ├ ─ ─ H E A D │ ├ ─ ─ h o o k s │ ├ ─ ─ i n d e x │ ├ ─ ─ i n f o │ ├ ─ ─ l o g s │ ├ ─ ─ o b j e c t s │ ├ ─ ─ O R I G _ H E A D │ ├ ─ ─ p a c k e d ­ r e f s │ └ ─ ─ r e f s ├ ─ ─ . g i t i g n o r e └ ─ ─ h e l l o . c
19. .git HelloGit_App hello.c hello.h world.c working tree Working Tree • HelloGit_App - Our project • .git - the database • working tree - where we are working on. • Check out source code from .git to working tree
20. Lets Talk About Git
21. 450e22 f17364 be6238 .git checkout hello.c hello.h world.c working tree Git Checkout Check a commit from repository • $ git checkout be6238
22. 450e22 f17364 be6238 .git hello.c hello.h world.c working tree foo.c Changed !! bar.c Git Status If working tree was modified - Changed !
23. 450e22 f17364 be6238 commit !!! 450e22 f17364 be6238 dead42 .git Git Commit Create a new commit to history and Write Log
24. Git Add What to commit? 1. $ git add foo.c 2. $ git add bar.c 3. $ git commit
25. .git .git .git .git Git is distribute • Everyone works in his own repository - locally • Push / Fetch objects to/from remote
26. .git .git push fetch commit checkout Push and Fetch • Git push - sends you commits to remote • Git fetch - retrieve commits from remote
27. .git .git github .git bitbucket Git Push • Git push - sends you commits to remote • $ git push bitbucket • $ git push github By default, you can only push to bare repository unless you config receive.denyCurrentBranch
28. .git .git github .git bitbucket Git Fetch • Git fetch - retrieve commits from remote • $ git fetch bitbucket • $ git fetch github
29. Power of Git • branch • merge • rebase
30. 450e22 f17364 be6238 master 450e22 f17364 be6238 cc0f38 master Git Branch(1) • master branch - default branch • master is like a pointer refer to the latest commit of a branch
31. 450e22 f17364 be6238 cc0f38 master f1038a 578bb1 4398cb 55670a fix_bug feature Git Branch(2) • We could have lots of branches • $ git branch feature • $ git commit # commit something • $ git checkout master # switch back to master branch
32. 450e22 f17364 be6238 cc0f38 master f1038a 578bb1 ffbbca fix_bug Git Merge • If we are in master, wanna merge fix_bug • $ git merge fix_bug
33. 450e22 f17364 be6238 cc0f38 master f1038a 578bb1 fix_bug 450e22 f17364 c09187a 7b6c51 master f1038a 578bb1 fix_bug Git Rebase • If we are in master, wanna rebase fix_bug • $ git rebase fix_bug
34. Git Flow • When creating new feature, fixing bug - in new branch • When finishing, merge back to master branch • To keep master branch as stable as possible
35. Basic Flow Use ‘SourceTree’ to 1. Clone a git repository 2. Read log 3. Modify the source code 4. Commit to repository 5. Push to remote repository
36. Config Name and Email • Tools / Options • Enter your name and email address • These information will be saved along with your commit
37. Clone Repository • Source • Destination
38. Read Log • Commit message • Commit content
39. Modify Source Code • Modify hello.c by editor • Working Copy displays what changed
40. Add Changed Files • Add hello.c by dragging
41. Commit Changes • Click Commit in Top-Bar • Write commit message
42. Ready to Push • We have 1 more commit and are ahead of remote branch • Click Push push your changes to remote
43. Make a branch 1. create a branch ‘new_feature’ 2. commit to new branch 3. checkout master - Boss wants to demo 4. checkout new_feature 5. merge to master
44. We used to • Manage branches that many people work on • Code review (pull request) • Merge/Split/Modify commits (git rebase -i) • Export an archive of specific commit/tag (git archive) • To trace who wrote the code which defect program (git blame) • Compare changes between two commits (git diff)
45. More Commands • $ git amend • $ git rebase -i • $ git bisect • $ git cherry-pick • $ git format-patch / am • $ git archive • $ git diff • $ git help ..
46. Reference • Sourcetree introduction