Git Basics

Git Basics presentation by Ramesh Dahiya during PHP Reboot's 'Working with Git' meetup on December 20th, 2014.

Transcript

1. Git PHP REBOOT Ramesh Dahiya PHP REBOOT 1
2. Special thanks - Sponsors GITHUB GRACIOUS SOFT Ramesh Dahiya PHP REBOOT 2
3. Short intro Ramesh Dahiya Technical Lead Ansh Systems Pvt. Ltd. Skype: dahiyabecomp Email:dahiyabecomp@gmail.com Github: https://github.com/credulus Twitter: https://twitter.com/dahiyabecomp Linked in: http://in.linkedin.com/in/rameshdahiya Ramesh Dahiya PHP REBOOT 3
4. Version Control System What is Version Control System? Ramesh Dahiya PHP REBOOT 4 Version control is a system which records changes to a file or set of files over time so that you can recall specific versions later. Types of version control systems: Local version control systems Centralized version control systems Distributed version control systems
5. History Generation Networking Operations Concurrency Examples First None One file at a time Locks RCS, SCCS Second Centralized Multi-file Merge before commit CVS, SourceSafe, Subversion, Team Foundation Server Third Distributed Changesets Commit before merge Bazaar, Git, Mercurial Ramesh Dahiya PHP REBOOT 5
6. Local VCS Earliest version control system was to copy files in another directory; Simplest but error prone. ‘rcs’ was one of the initial and most popular Local version control systems. This tool basically works by keeping patch sets from one change to another in a special format of disk. Biggest disadvantage: No collaboration, only single developer could work on that. Ramesh Dahiya PHP REBOOT 6
7. Centralized VCS Centralized version control system solved biggest problem of collaboration. It have central server which have all files. Examples are CVS, Subversion, MS VSS etc. Biggest disadvantage: Single point of failure. Ramesh Dahiya PHP REBOOT 7
8. Distributed VCS In Distributed VCS, clients don’t just checkout the latest snapshot of the files but they fully mirror the repository. If server fails, any client copy can be used to restore the server. Example Git, Marcurial, Bazaar, Darcs. Ramesh Dahiya PHP REBOOT 8
9. Disadvantage of CVCS You can’t commit without merge and merging is a pain. Ramesh Dahiya PHP REBOOT 9 No way to push changes to another user (without submitting to the Central Server) Subversion fails to merge changes when files or directories are renamed. Offline commits are not possible. .svn files pollute local directories. The trunk/tags/branches convention can be considered misleading. Performance and Single point of failure.
10. Disadvantages of DVCS If a project contains many large, binary files that cannot be easily compressed, the space needed to store all versions of these files can accumulate quickly. If a project has a very long history (50,000 changesets or more), downloading the entire history can take long time and disk space. Ramesh Dahiya PHP REBOOT 10
11. History of Git Till 2005, Linux Kernel was using proprietary DVCS BitKeeper. In 2005, that relationship broke as BitKeeper revoke ‘free of charge’ status and Git borned with goals: Speed Simple design Strong support for non-linear branches Fully distributed Able to handle large projects like Linux Kernel efficiently Ensure Integrity Ramesh Dahiya PHP REBOOT 11
12. Advantages of Git Distributed Fully distributed (Almost) Everything is local Everything is fast Every clone is a backup Work Offline – No network needed for Performing the diff View file history Committing changes Merging branches Obtaining other version of file Switching branches Ramesh Dahiya PHP REBOOT 12
13. Advantages of Git Immutable (Almost) Never remove the data Ramesh Dahiya PHP REBOOT 13
14. Advantages of Git Snapshot – Not patches File based delta storage Ramesh Dahiya PHP REBOOT 14
15. Advantages of Git Snapshot – Not patches Ramesh Dahiya PHP REBOOT 15 Deltaset in SVN or most other CVCS
16. Advantages of Git Snapshot – Not patches Ramesh Dahiya PHP REBOOT 16 Snapshot in git
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26. Ramesh Dahiya PHP REBOOT 26 SVN Git
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32. Ramesh Dahiya PHP REBOOT 32 SVN Git
33. Git: First step FOR DEVELOPERS Ramesh Dahiya PHP REBOOT 33
34. Installation On linux, Git is mostly pre installed. However if needed, it can be installed with following commands: RedHat based Linux sudo yum install git-core Debian based Linux sudo apt-get install git-core Windows Download installer from code.google.com/p/msysgit Mac brew install git Ramesh Dahiya PHP REBOOT 34
35. Configuration Git have three different configuration levels: System configuration: located at /etc/gitconfig file. These configuration settings apply to all users. --system option passed to git config command to access system configuration. User specific or global configuration: located at ~/.gitconfig file. This config is applicable to all repositories of single user. --global optn passed tp git config command to access global Repository configuration: located in .git/config file. Apply to single repository. Ramesh Dahiya PHP REBOOT 35
36. git config command Identity git config --global user.name "Kapil Sharma" git config --global user.email "kapil@kapilsharma.info" Editor git config --global core.editor netbeans Ramesh Dahiya PHP REBOOT 36
37. States Modified Staged Committed Ramesh Dahiya PHP REBOOT 37
38. State flow Ramesh Dahiya PHP REBOOT 38
39. GitHub Github is a free Git server for open source git repository. git clone https://github.com/kapilsharma/gittestrepo.git Initialize locally git init Create some file, say readme.txt git add readme.txt git commit –m “First commit” git remote add https://github.com/kapilsharma/gittestrepo.git Ramesh Dahiya PHP REBOOT 39
40. Basic Operation Make clone git clone https://github.com/kapilsharma/gittestrepo.git <- Unmodified Make changes Add a new file, say test1.php. <-Untracked Edit existing file, say test2.php. <- Modified Stage Changes git add test1.php <-Staged git add test2.php <-Staged Commit Git commit –m "Change message" <- Unmodified Ramesh Dahiya PHP REBOOT 40
41. Communicate with origin Origin: Central server from where you checkout code. (Assum for now) Publish changes on origin git push origin master Get changes from origin git pull origin master Ramesh Dahiya PHP REBOOT 41
42. Gitignore file Some times there are files that we need locally but don’t want to commit. Example of such files are: Configuration files IDE files like .nbproject, .subline-project Local documents Libraries of framework To command git not to consider these files, we simple create file '.gitignore‘ can commit it at the root. Ramesh Dahiya PHP REBOOT 42
43. Logs Entire (paged) git log Date filtering git log --since=2.weeks git log --since="2 years 1 day 3 minutes ago“ git log --since='2012-12-01' --until='2012-12-10' Ramesh Dahiya PHP REBOOT 43
44. Quick revision Action Stage Command Stage files Modified -> staged git add filename Review your changes git status git log git diff Commit Staged -> unmodified git commit –m "message" Stage and commit Modified -> staged ->unmodified git commit –a –m "message" Ramesh Dahiya PHP REBOOT 44
45. Reverting changes Ramesh Dahiya PHP REBOOT 45
46. Reverting changes Unstage staged file git reset HEAD test.php Unmodify modified file git checkout – test.php Revert commit git revert 1234a2 Add to last commit git commit --amend Ramesh Dahiya PHP REBOOT 46
47. Removing/Move files To remove a file git rm filename To remove file from git but keep on harddisk git rm –cached filename To move/rename file git mv filename newfilename Above command is equivalent to mv filename newfilename git rm filename git add newfilename Ramesh Dahiya PHP REBOOT 47
48. Remote git push origin master - git push repository branch git remote git remote -v git remote add remotename remoteurl git fetch remotename Ramesh Dahiya PHP REBOOT 48
49. Ramesh Dahiya PHP REBOOT 49 Well, not with Git
50. Tags Tags is just a marker in revision history, to mark important points of software, like versions. Listing tags: git tag Listing tags with patterns git tag -l "1.2.*" Git support two type of tags Annotated tags – can give a message with tag. (Lightweight) tags Ramesh Dahiya PHP REBOOT 50
51. Creating tags Lightweight tags git tag tagname Annotated tag git tag –a tagname –m "message" Ramesh Dahiya PHP REBOOT 51
52. Pushing tags Git tags, when created are local. Like any other commit, we need to push them to remote repository. Command git push origin tagname If we want to push all local tags, command is git push origin --tags Ramesh Dahiya PHP REBOOT 52
53. Branches Branching means you diverge from the main line of development and continue to do work without messing with that main line. Branching in most SCM is expansive process. Some people believe branching in Git is its Killer Feature. The way Git branches is incredibly lightweight. Ramesh Dahiya PHP REBOOT 53
54. Branches Lets assume we are working on a project and already have two commits. ----------------- Now say you have to work on mantis issue 53 (just for example) Lets create iss53 branch. Ramesh Dahiya PHP REBOOT 54
55. Branches Creating branch Ramesh Dahiya PHP REBOOT 55 Create branch git branch iss53 Switch to branch git checkout iss53 Above two commands can be merged in single command as git checkout –b iss53
56. Branches New branch. ----------------- Now lets make some changes in new branch and commit. Ramesh Dahiya PHP REBOOT 56
57. Branches New branch after changes. ---------------------- OOPs we got an urgent fire bug on site. It needs to be fixed immediately. Lets create new branch form master. Ramesh Dahiya PHP REBOOT 57
58. Branches Creating new branch And fix the issue Ramesh Dahiya PHP REBOOT 58 First go back to master git checkout master Create new branch git checkout –b hotfix We can now fix the issue on hotfix branch.
59. Branches New condition. ------------------ Now we need to release hotfix. However only master should contain the code to be released. So lets merge hotfix branch to master. Ramesh Dahiya PHP REBOOT 59
60. Branches Marge hotfix to master ------------------- Ramesh Dahiya PHP REBOOT 60 First go back to master git checkout master Now merge hotfix to master git merge hotfix
61. Branches Hotfix merged ------------------ Now hotfix branch is useless, lets delete it. Then lets go to iss53 branch and finish development there. Ramesh Dahiya PHP REBOOT 61
62. Branches Development on iss53 branch ------------------- Ramesh Dahiya PHP REBOOT 62 First go back to iss53 branch git checkout iss53 Make some changes there to finish development and commit
63. Branches Iss53 branch ------------------ Now development is finished on iss53 branch and we need to merge it back to master. BUT There is a problem. Ramesh Dahiya PHP REBOOT 63
64. Branches Iss53 branch ------------------ Master and iss53 branch do not have common ancestor. Ramesh Dahiya PHP REBOOT 64
65. Branches Merge iss53 in master Assuming no conflict ------------------- Ramesh Dahiya PHP REBOOT 65 First go back to master git checkout master Merge iss53 branch git merge iss53
66. Branches Iss53 -> master merge ------------------ And if needed, delete iss53 branch Ramesh Dahiya PHP REBOOT 66 git branch -d iss53
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