getting into git
DESCRIPTION
This was a presentation I gave at the 2012 NorthEast PHP conference, in Cambridge, MA.TRANSCRIPT
Getting Into Git8/11/2012
Rick [email protected]@rickumalihttp://tech.rickumali.com/
This presentation is on Google Drive at:
http://sn.im/git-talk-2012
There you can read the 'speaker notes' for this presentation. You can also provide feedback at:
https://joind.in/6830
Questions I Plan to Answer
What is source control?
What is the big deal with Git?
Can you show me a little Git?Commits. Branches. Merges. Remote repos.
What is Source Control?
Source code control is the most important practice a coding professional can do.
A mechanism to track changes in source code.
Used for version history, auditing, and recovery.
Revision Control Example: Wiki
Revision Control Example: Git
This is what we'll be trying.
Git
Git is an open source, distributed version control system designed for speed and efficiency.
● Freedom● No "server" required● Unique architecture
Installing Git
http://git-scm.com/book/en/Getting-Started-Installing-Git
The installation is very easy!
Warning: Command Line Ahead
Our Example: A Basic Drupal Module
Creating a "Repository"
Let's pretend we're developing a Drupal module.
% cd web/sites/all/modules% mkdir dumpstamp% cd dumpstamp% git init
"git init" creates the entire Git repository. No server interaction required!
Committing Your First File
To 'commit' means 'to save the state' of your work. You must first 'add' this change to the 'staging area'.
% vi README.txt% git add README.txt% git commit -m "First commit. README file."
Use 'git help' to learn all the switches. -m stands for message.
Looking at the Repository History
% git log
Each 'commit' contains an ID, along with the author information from earlier, and a time stamp.
% gitk
GUI tools can help you visualize the 'repo.'
Adding More Files
% vi dumpstamp.info dumpstamp.module% git status% git add .% git commit
This second commit saves the work of adding two files by using 'git add .'.
The .module and .info files are the two required files for every Drupal module.
Enabling Our Drupal Module% drush pm-info dumpstamp
% drush pm-enable dumpstamp
Examining Changes to Files
% vi dumpstamp.module% git status% git diff% git add dumpstamp.module% git commit% git log
The above is a typical 'workflow'.
Git offers suggestions and hints as you use it.
Doing More Changes
% vi dumpstamp.module% git diff% git commit -a
Or even:
% git commit -a -m "Commit message."
Another typical 'workflow'.
Looking at the Log Again
The history can be examined different ways.
% git log% git log --format=short% git log --format=oneline% git log --oneline
Revisiting History
You can 'revisit' any point of your history.
% git checkout SHAID
Every commit is known by its SHA ID.
This is the first step in making a branch! (Use git checkout master to revert.)
Branching and Merging Next, But...
What we have covered so far is probably 70-80% of what you will do with git.
Adding and committing files are the heart of git (and any version control system).
Git encourages experimentation, by making branching very easy.
Branching
Branching: git branch
% git branch BRANCH SHA1% git checkout BRANCH
Make some edits on a change below the master, then commit.
git branch makes a branch from the branch you're on (default branch is 'master').
Branching: Starting State
SHA 1Amaster
NOTE: 'master' is a branch that's created 'by default'.
Branching: Make Some Changes
SHA 1A
SHA 2Bmaster
git commit
Branching: Making a Branch
SHA 1A
SHA 2Bmaster
branch1
git branch "branch1" SHA1Agit checkout "branch1"
OR git checkout -b branch1 SHA1A
Branching: Changes on the Branch
SHA 1A
SHA 2Bmaster branch1SHA 3C
(Make changes in "branch1".)git commit
Visualizing the Branches
Merging
Bringing two branches together.
First 'checkout' the branch you want to merge into (typically master), then 'merge' the branch.
% git checkout master% git merge BRANCH
Merging: Starting State
SHA 1A
SHA 2Bmaster branch1SHA 3C
Merging: Two Steps
SHA 1A
SHA 2B
master
branch1SHA 3C
SHA 4D
git checkout mastergit merge branch1
Merging: The Hard Part
Manual 'merging' may be required.
Visualizing the Merge
Whew!
Remote Branches
You can 'browse' public Git repositories for code that you want to examine or use.
You can upload a local Git repository to a public Git repository.
Common Public Git Repositories
Uploading Code (to Github)
Create a key pair on your machine.
Create a repository (on Github).
Add a 'remote' (via git remote add).
Upload your code (via git push).
Creating a Key Pair
Creating a Repository
Adding a Remote, then Upload
Next Steps
Install Git.
Commit your code changes frequently.
Log verbosely (in commit messages).
Experiment (branch) often.
Resources
http://git-scm.org/Both "Pro Git" book, and Git reference
http://gitref.org/A "quicker" Git reference
http://www-cs-students.stanford.edu/~blynn/gitmagic/"Friendlier" Git walk-through (git magic).
http://drupal.org/node/803746A workflow for using Git with Drupal.
http://www.mail-archive.com/[email protected]/msg39091.html
Linus on "clean history."
Resources
http://www.youtube.com/watch?v=4XpnKHJAok8Linus Torvalds (Git creator) (May '07)
http://www.youtube.com/watch?v=8dhZ9BXQgc4Randal Schwartz (Perl expert and Git old-timer) (Oct
'07)http://www.youtube.com/watch?v=ZDR433b0HJY
Scott Chacon (Pro Git author) (July '11)