practical git for developers

Practical git for developers(aka 'Git for beginners')

Wim GoddenCu.be Solutions@wimgtr

Who am I ?

Wim Godden (@wimgtr)

Where I'm from

Where I'm from

Where I'm from

Where I'm from

Where I'm from

Where I'm from

My town

My town

Belgium the traffic

Who am I ?

Wim Godden (@wimgtr)

Founder of Cu.be Solutions (http://cu.be)

Open Source developer since 1997

Developer of PHPCompatibility, OpenX, PHPConsistent, ...

Speaker at Open Source conferences

Who are you ?

Developers ?

CVS ?

SVN ?

TFS ?

Git ?

What is git ?

Git is a file system with a Version Control System on top of it

Git's file structure

Commit

treeauthor_infoparent

Tree

README.MDLICENSEindex.php

Blob

datadatadata...

Blob

datadatadata...

Blob

datadatadata...

6d3af...

8a3ea...

901a3...

4a39c...

e3231...

8a3ea...

901a3...

4a39c...

e3231...

What is git ?

Git is a file system with a Version Control System on top of it

What is git ?

Git is a distributed file system with a Version Control System on top of it

(Almost) everything is local

Clone = copy of entire repository

Work offline :Perform a diff

View file history

Commit changes (!)

Create, merge or switch branches

etc.

Only push/pull are not local

(Almost) everything is immutable

Immutable = doesn't change

Once placed in git, it stays there

Even if you delete files

Differences with SVN

SVN keeps diffs between versions

Git keeps full snapshots

Commit #1


Tree

README.MD

Commit #2


Tree

README.MDindex.php

Commit #3


Tree


Differences with SVN

SVN is centralized Git is distributed

An SVN commit shared with everyone A Git commit is local

SVN has revision increments Git has SHA1 hashes to identify objects(commits, trees, blobs, ...)

Basic git config

$ git config --global user.name "Wim Godden"$ git config --global user.email "[email protected]"

$ git config --global core.editor vim

$ git config --global core.autocrlf input$ git config --global core.autocrlf true

$ git config --global color.ui true

(on Linux)

(on Windows)

Basic git - .gitignore

Allows you to specify files to ignore

Can be specific to repository

Hint : set up a global .gitignore for :thumbnail.dat

desktop.ini

.DS_Store

Your local editor's files

Create a repo

$ git init

$ tree .git.git/ branches config description HEAD info exclude objects info pack refs heads tags

.git directory

config Configuration file

refs/heads/... - branches

refs/tags/... - tags

refs/remotes/... - remotes

objects/... - the actual objects

HEAD the current working space, points to one of branches

git clone

Creates a repository from an existing repository

git clone https://someplace.com/repo.git

Original repository is called 'origin' This is called a 'remote'

git clone [email protected]:wimg/confoodemo.git

Git flow

Working directoryStaging areaRepositoryRemote(s)AddCommitPush

git status

Simple command

Explains in clear language what's going on

Use it, use it, use it, ...

Git flow


git add

Add file in current state to the staging area

Can be new file

Can be modification

git add -A stages all

git add . stages new and modified, but no deletions

git add -u stages modified and deleted, but no new files

git reset

Unstage changes

Revert to older commit version

Beware : dangerous command !

Remove files from repository

2 ways :Delete, then rmDelete the file from working directory

git rm

Commit

Just rmgit rm

Commit

Accidentially deleted ? git checkout --

Git flow


git commit

Creates a new version

Based on the staging area

Commits on local repository only

Commit #1


Tree

README.MD

Commit #2

treeauthor_infoparent : #1

Tree

README.MDindex.php

Commit #3

treeauthor_infoparent : #2

Tree


HEAD

git log

Shows each commit with SHA1 hash hash can be used with other commands

-p gives a diff view

git diff

No params : default diff output

git diff --staged : diff with what's been staged

Clone, add, commit and push

C1Remote origin

Local repository

C2

master

C1C2

origin/master

12C1C2

origin/master

C3

masterHEAD

masterHEAD

12C1C2

master

C1C2

origin/master

C3

masterHEAD

33C1C2

master

C3

Working with remotes

git push Send locally commited changes to the remote repository

git fetch/pull Retrieve changes from the remote repository

Fetch, merge and pull

Remote origin

Local repository

C1C2

origin/master

12C1C2

origin/masterC3

masterHEAD

masterHEAD

1C1C2

C3

masterHEAD

23C1C2

master

C3

C2

origin/master

3

git fetch + merge vs git pull

git fetch : fetches information from remote into local repository but nothing more

git merge : merges changes that were fetched needs a source parameter merges TO wherever HEAD is pointing to : git merge origin/master

git pull : does both at the same time

Branches

Branches are separate full-blown versions of your code

Default branch = master

Which branches are there ? git branch

Create a new branch git branch

Switch to branch git checkout

Create + switch to new branch git checkout -b

Show branch activity : git show-branch

Delete a branch : git branch -d

* = current brach+ = commit is in the branch- = commit is in the branch as a merge

Merging changes in a project

C1C2

origin/master

C1C2

origin/masterC3

master

master

C4

test

LICENSE : added paragraph 1

LICENSE : added paragraph 2

C1C2

origin/masterC3

master

C4

test

LICENSE : added paragraph 1 + 2

Edited LICENSE

C5

Conflicting change

git merge conflict

git status shows conflicted files

Resolve conflict

git commit -a tells git conflict was resolved

git checkout -b testedit LICENSE filegit checkout masteredit LICENSE filegit merge test will show conflictgit status will show unmerged pathedit LICENSE filegit commit -a -m'conflict resolved'

Contributing to a Github project

Github is built on Git, so...

Clone, commit, pull, merge, push are all the same

But :

You need to fork the project first

Changes to the main repository must be requested through a pull request

Creating a fork

Creating a fork

Will create a complete copy (not a clone) of the projectIncluding master, all branches, all tags, all commits, etc.

i.e. confoo/some-repo /some-repo

You can do anything in it...

But please don't if you intend to contribute back...

Which you should ofcourse ;-)

Next : create a branch for your feature/bugfix

Why ?Work on multiple features/fixes at same time

Experiment without damaging your master

master should always be a fully functioning, deployable version

Name the branch wellDon't : bugfix

Do : bugfix_issue_26_fatal_error

Next : add/change code and commit

Don't forget unit tests, integration tests,

Make your commit message descriptiveDon't : fixed it

Do : added real-time updates on dashboard

Each commit should contain a single feature or bugfix Allows project maintainers to add small blocks of code Easier than adding 50 features/bugfixes Easier to test

Next : create a Pull Request (PR)

When you want to contribute

Partial code = OK But only if you want feedback

Otherwise :Finish your code

Make sure you have unit tests

Be descriptive in your pull requestDon't : this will fix my issues

Do : Added an OAuth authentication layer

Next : merging the PR

Done by a project maintainer (could be you !)

Merge from the PR branch to master

Again : have a clear merge message On Github : 'Closes #56' will close Github issue and links

Congratulations, you're a Github contributor ;-)

Git tools

git-cola (Linux, Win, Mac)

GitHub Desktop (Win, Mac)

GitKraken (Linux, Win, Mac) - beta

Liquid prompt

Useful list : https://git.wiki.kernel.org/index.php/Interfaces,_frontends,_and_tools

Questions ?

Questions ?

Thanks !

@wimgtr

[email protected]

practical git for developers

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