# Git

# Basics

## Bare basics

#### semantic versioning
[https://semver.org/](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](https://git-scm.com/docs/git-switch)
  * `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`:
```config
[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
```bash
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](https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration#_core_autocrlf)

#### 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

[![](https://bookstack.draab.at/uploads/images/gallery/2022-10/scaled-1680-/image-1666903428458.png)](https://bookstack.draab.at/uploads/images/gallery/2022-10/image-1666903428458.png)


[![](https://bookstack.draab.at/uploads/images/gallery/2022-10/scaled-1680-/image-1666903459287.png)](https://bookstack.draab.at/uploads/images/gallery/2022-10/image-1666903459287.png)

# Stash / Worktree

## git stash


## git worktree
[git](https://git-scm.com/docs/git-worktree)
[gitkraken](https://www.gitkraken.com/learn/git/git-worktree)
[use](https://www.hsbi.de/elearning/data/FH-Bielefeld/lm_data/lm_1359639/git/worktree.html)

### 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

```bash
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)

```bash
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
```conf
[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
  ```bash
  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`
  ```sh
  #!/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`
  ```sh
  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](https://github.com/jesseduffield/lazygit)

## 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](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:
```bash
git clone https://myrepo.com/git.git temp
mv temp/.git code/.git
rm -rf temp
```
* without clone (use fetch):
```bash
git init
git remote add origin {{url_of_clone_source}}
git fetch origin
git checkout master # delete files that are blocking
```