Git

• Basics
• Stash / Worktree
• Merge, Rebase, Reset, Clean
• Hooks
• GUI / visualize
• Github / Gitlab
• Special usecases

Basics

Bare basics

semantic versioning

https://semver.org/

clone

• git clone <url> clone an arbitrary repository

add

• git add . add all files to stage

commit

• git commit -m "some commit message" commit staged changes with inline commit message

checkout -> switch

• switch: git-scm.com

  • git switch -c <branch-name> create new branch and switch to it

• checkout:

  • git checkout <branch-name> checkout the branch with given name
  • git checkout -b <branch-name> create and checkout a new branch with given name

remotes

• git push
• git fetch
• git pull

log

git log

• --graph show visual graph in the terminal
• --all list all branches, not only current branch

alias in ~/.gitconfig:

[alias]
lg1 = log --graph --abbrev-commit --decorate --format=format:'%C(bold blue)%h%C(reset) - %C(bold green)(%ar)%C(reset) %C(white)%s%C(reset) %C(dim white)- %an%C(reset)%C(auto)%d%C(reset)' --all
lg2 = log --graph --abbrev-commit --decorate --format=format:'%C(bold blue)%h%C(reset) - %C(bold cyan)%aD%C(reset) %C(bold green)(%ar)%C(reset)%C(auto)%d%C(reset)%n''          %C(white)%s%C(reset) %C(dim white)- %an%C(reset)'
lg = lg1

config

local

git config user.email "your_email@abc.example"
git config user.name "Example Name"

filemode

ignore filemod: git config (--global) core.fileMode false

lineend

on linux: git config --global core.autocrlf input

on windows: git config --global core.autocrlf true

to keep LF as end of line in the repo. check git docs

store credentials

• in plaintext in ~/.git-credentials
  • git config --global credential.helper store
  • add personal accesstoken to credetinal files:

    git credential approve << EOF
    protocol=https
    host=gitlab.com
    username=private-token
    password=<<your personal access token>>
    EOF
    

  • content in files:

  # ~/.gitconfig
  [user]
      email = myMail@mymail.com
      name = Me
  [credential]
      helper = store
  
  # ~/.git-credentials
  https://private-token:............@gitlab.com
  

• in cache
  • git config credential.helper 'cache --timeout=<timeout>'
  • timeout in seconds (default 900 sec)

others

Stash / Worktree

git stash

git worktree

git gitkraken use

add new worktree

git worktree add <path> <branch>

• --force force creating a new worktree (e.g. create new worktree with already checked out branch)

list worktrees

git worktree list

remove unused worktree

git worktree remove [-f] <worktree>

• Unclean worktrees or ones with submodules can be removed with --force or -f.

Merge, Rebase, Reset, Clean

merge vs rebase

https://www.atlassian.com/git/tutorials/merging-vs-rebasing

Make the current Git branch a master branch

git checkout better_branch
git merge --strategy=ours master    # keep the content of this branch, but record a merge
git checkout master
git merge better_branch             # fast-forward master up to the merge

rename branch (local and remote)

• git branch -m master main - rename master to main
• git push -u origin main - push branch with new name
• set remote default branch in remote repo.
• protect new brunch, unprotect old branch (in remote repo)
• git push origin --delete master - delete branch in remote repo

reset last commit(s)

• undo the last commit (changes will be in place)
• git reset --soft HEAD~
• git reset --soft HEAD~2 undo the last two commits

merge (force remote)

• drop local changes (incl commits)

git fetch --all
git reset --hard origin/master

mergetool

• installed merge tool like meld necessary
  • sudo apt install meld
  • configure it: https://stackoverflow.com/questions/34119866/setting-up-and-using-meld-as-your-git-difftool-and-mergetool

[diff]
    tool = meld
[difftool]
    prompt = false
[difftool "meld"]
    cmd = meld "$LOCAL" "$REMOTE"
    
[merge]
    tool = meld
[mergetool "meld"]
    # Choose one of these 2 lines (not both!) explained below.
    cmd = meld "$LOCAL" "$MERGED" "$REMOTE" --output "$MERGED"
 #   cmd = meld "$LOCAL" "$BASE" "$REMOTE" --output "$MERGED"

• merge

  git checkout master
  git merge branch_name
  

  • start mergetool: git mergetool
• diff
  • git difftool BRANCH_NAME -- FILE

clean up

git clean -d -x ( -n | -i | -f )

will remove untracked files

• including directories (-d)
• files ignored by git (-x)
• -n, -i or -f must be specified
  • perform a dry-run (-n)
  • interactive mode (-i)
  • delete all without asking (-f)

Hooks

git hooks

pre-commit-msg

This example adds the branch name as prefix to the commit message:

• create the file ~/.githooks/prepare-commit-msg

  #!/bin/sh
  #
  # Automatically adds branch name every commit message.
  #
  NAME=$(git branch | grep '*' | sed 's/* //' | cut -d '_' -f 1)
  
  echo "[$NAME]"': '$(cat "$1") > "$1"
  

• make the file executable sudo chmod +x ~/.githooks/prepare-commit-msg
• execute git config --global core.hooksPath ~/.githooks to use this hook at every repository

pre-push example

• create the file ~/.githooks/pre-push

  while true; do
      read -r -p "Have you executed 'composer test' already? (y|n): " yn < /dev/tty
      case $yn in
          [Yy]*) exit 0 ;;
          [Nn]*)
          echo "\e[31mPlease execute the command first \e[39m";
          exit 1;
          ;;
          *) echo "Please answer [y]es or [n]o." ;;
      esac
  done
  

• execute git config --global core.hooksPath ~/.githooks to use this hook at every repository

GUI / visualize

CLI ui

show logs in a graph

git log --oneline --graph --color --all --decorate

for linux use alias gg="git log --oneline --graph --color --all --decorate" in ~/.bashrc

lazygit

lazygit on Github

GUI

Github / Gitlab

Common

create patch from commit

add

• .patch for a patch file or
• .diff for a plain diff file

as a suffix onto commit links or merge request links.

examples:

• https://github.com/magento/magento2/commit/18dee3d979ed8ee68a44324e892e6b7f570c987c.diff

Gitlab special

gitlab personal access token

• go to https://gitlab.com/-/profile/personal_access_tokens
  • rights: read_repository and write_repository
  • add line in ~/.git-credentials: https://private-token:{{token}}@gitlab.com

Special usecases

rename branch

• git checkout <old_name>
• git branch -m <new_name> (move/rename the local branch)
• git push origin -u <new_name> (push new branch to remote)
• git push origin --delete <old_name> (remove old branch from remote)

clone repo in existing folder

• with clone:

git clone https://myrepo.com/git.git temp
mv temp/.git code/.git
rm -rf temp

• without clone (use fetch):

git init
git remote add origin {{url_of_clone_source}}
git fetch origin
git checkout master # delete files that are blocking