Git

Advanced training

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Summary

I. Basics

II. HOWTOs

III. Git Flow

IV. Tips

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Basics

• Distributed != Centralised

• Basic commands

$ git init
$ git status
$ git add <filepath>
$ git commit -m <message>
$ git push <remote> <branch>

• Ignore files : .gitignore

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HOWTOs

• How to setup git ?

$ git config --global user.name <username>
$ git config --global user.email <email>

• How to choose my editor ?

$ git config --global core.editor vim

• How to generate a ssh key ?

$ ssh-keygen -t rsa -b 4096 -C <email>

• How to add a remote repository ?

$ git remote add origin git@github.com:<user>/<repo>.git

• How to change a remote repository url ?

$ git remote set-url origin git@github.com:<user>/<repo>.git

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HOWTOs

• How to untrack a file without deleting it ?

$ echo <filename> >> .gitignore
$ git rm --cached <filename>

• How to view my local changes ?

$ git diff

• How to view the commit list ?

$ git log --oneline --decorate --graph

• How to pull without having to commit ?

$ git stash
$ git pull <remote> <branch>
$ git stash pop

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HOWTOs

• How to create a branch ?

$ git checkout -b <branch>

• How to keep a file in the repository but disable change tracking ?

$ git update-index --assume-unchanged <filename>

• How to reactivate change tracking ?

$ git update-index --no-assume-unchanged <filename>

• How to edit my last commit ? (I forgot one file, I made a typo in the commit message)

$ git add <file>
$ git commit --amend
# or if I don't want to change the commit message
$ git commit --amend --no-edit

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HOWTOs

• How to undo my changes ?

$ git status
# Before ``git add``
$ git checkout -- <filename>
# After ``git add``
$ git reset HEAD <filename>
$ git checkout -- <filename>

• How to uncommit ?

# If I want to keep my changes
$ git reset --soft HEAD~1
# If I want to delete my changes
$ git reset --hard HEAD~1
# Then if I have already pushed to the remote repository
# I may need to disable branch protection
$ git push <remote> <branch> -f

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HOWTOs

• How to merge a list of commit ?

$ git rebase -i HEAD~<numberOfCommits>
pick 1b68a67 :bug: Fix #27
squash 6b36b82 :wrench: Replace config files with env variables.
squash 3da99cc :heavy_minus_sign: :heavy_plus_sign: Replace node-uuid by uuid
squash 5e6c751 :arrow_up: Upgrading dependencies
# Rebase 479f697..5e6c751 onto 479f697 (4 command(s))
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
# d, drop = remove commit

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HOWTOs

• How to pull commits from a remote repository without creating a merge commit ?

# git pull = git fetch + git merge
# git pull --rebase = git fetch + git rebase
$ git pull --rebase <remote> <branch>

• How to set rebase as default ?

$ git config --global pull.rebase true

• How to solve conflict when rebasing ?

$ git pull
# Snap! Conflict!
$ vim <filename>
$ git add <filename>
$ git rebase --continue
# Or if I want to abort
$ git rebase --abort

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HOWTOs

• How to run some scripts before committing ?

$ mv .git/hooks/precommit.sample .git/hooks/precommit
$ vim .git/hooks/precommit
#!/bin/bash
npm run lint
npm run test
npm run build

• Git hooks are very handy to run scripts before or after some events :
  • pre-commit
  • pre-push
  • pre-rebase
  • prepare-commit-msg

</script>

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Git Flow

• Master : protected production branch
• Develop : protected staging branch
• Feature branches :

# Create
$ git checkout -b <featurename> develop
# Merging
$ git checkout develop
$ git merge --no-ff <featurename>
$ git branch -d <featurename>
$ git push origin develop

• Release branches : naming convention e.g release-

$ git checkout -b release-<version> develop
# Bump version number
$ git commit -a -m "Bumped version number to <version>"
$ git push origin release-<version>
# Merge in master
$ git checkout master
$ git merge --no-ff release-<version>
$ git tag -a 1.2
# Merge in develop
$ git checkout develop
$ git merge --no-ff release-<version>

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Git Flow

• Hotfix branches : naming convention e.g hotfix-

$ git checkout -b hotfix-<nextversion> master
# First bump the version
$ git commit -a -m "Bumped version number to <nextversion>"
# Then fix the bug
$ git commit -m "Fixed severe production problem"
# Merge in master
$ git checkout master
$ git merge --no-ff hotfix-<nextversion>
$ git tag -a <nextversion>
# Merge in develop or in current release branch if release branch hasn't been merged yet
$ git checkout develop
$ git merge --no-ff <nextversion>

• See Vincent Driessen's post for more details

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Git Flow

Main branches

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Git Flow

Feature branches

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Git Flow

Merge without ff

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Git Flow

Hotfixes branches

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Git Flow

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Advices

• Use rebase !
• Do not :

$ git add .
$ git commit -a

• Before committing always :

$ git status
$ git diff

• Use aliases

alias gst  ='git status'
alias gd   ='git diff'
alias gl   ='git pull'
alias ga   ='git add'
alias gc   = 'git commit -v'
alias gc!  ='git commit -v --amend'
alias gcn! ='git commit -v --no-edit --amend'
alias gp   ='git push'
alias gcb  ='git checkout -b'
alias glog ='git log --oneline --decorate --graph'

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Advices

• Use gitmoji
• Use git & github for your personnal projects to learn (like this presentation)

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The end.