IPS-DEV


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.footnote[
`IPS-DEV` - N. Dubray - ENSIIE - 2024 - [:book:](../index.html)
]

---

# Version control system: `git`

.hcenter.w15[![](images/git_logo.png)]

## History
* distributed version control system
* created by **Linus Torvalds** in 2005 as free software (GPL v2)
* initial goal: become the main VCS (Version Control System) of the **Linux kernel**
* today: **#1 VCS** :v:

## Characteristics
* strong support for non-linear development
* distributed development
* compatibility with existant systems and protocols
* efficient handling of large projects
* cryptographic authentication of history

.block[
* Repository: [https://github.com/git/git](https://github.com/git/git)
* Website: [https://git-scm.com](https://git-scm.com)
* License: `LGPL-2.1`
]

---

# `git` workflow

.mermaid[
    sequenceDiagram
        Remote-->>+Local repo: git clone/pull
        Note over Staged: Empty
        Local repo->>Files: git checkout
        Note over Files: Code...
        Files->>+Staged: git add/rm
        Staged->>-Local repo: git commit
        Note over Files: Code...
        Files->>+Staged: git add/rm
        Staged->>-Local repo: git commit
        Local repo-->>-Remote: git push
]

---

# Creation of a `git` repo from scratch

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<asciinema-player src="scripts/git_init.cast"></asciinema-player>
]


---

# Main `git` commands

## Configure `git` (should be done once)
```shell
$ git config --global user.name "Your Name"
$ git config --global user.email you@yourdomain.example.com
```

## Create a local repo
```shell
$ git init
```

## Clone a remote repo (and create a local repo)
```shell
$ git clone http://some.domain.com/path/to/repo.git
```

## Get documentation
```shell
$ # Example: documentation for command 'git clone'
$ git help clone
```

---

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# Typical `git` workflow

## 1. clone or create repo
```shell
$ git clone http://some.domain.com/path/to/repo.git
```
--

## 2. make some changes
```shell
$ vim README.md # create new file
$ vim main.cpp  # edit existing file
$ rm toto.h     # remove existing file
```
--

## 3. **stage** changes
```shell
$ git add main.cpp README.md
$ git rm toto.h
```
--

## 4. check staged changes
```shell
$ git diff
$ git status
```
--

## 5. commit staged changes
```shell
$ git commit  # will open an editor to enter the commit message
$ git commit -m "Commit message"
```

---

# `git` history

## View project history (CLI)
```shell
$ git log
$ git log --draw --oneline --color
```

<div data-dir='scripts/toto5' class='cinescript'></div>

---

# GUI tool `gitk`

.hcenter.w90.shadow[![](images/gitk_00.png)]

---

# GUI tool `gitg`

.hcenter.w90.shadow[![](images/gitg.png)]

---

# `git` branches

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## List branches
```shell
$ git branch
   dev
 * main
```

## Create a branch
```shell
$ git branch dev
```

## Switch to a branch
```shell
$ git checkout dev
```

## Create + switch to a branch
```shell
$ git checkout -b dev
```

## Merge a branch
```shell
$ git merge dev
```

## Delete a branch
```shell
$ git branch -d dev
```
]
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 <canvas id='gitExample0'></canvas>
]
]

---

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# How to use `git` branches

.row[
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* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
]

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 <canvas id='branchHowto0'></canvas>
]
]

---

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# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
```shell
$ git checkout -b newfunc
$ # some work
$ git commit -m "Commit D"
...
$ # some work
$ git commit -m "Commit F"
```
]

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 <canvas id='branchHowto1'></canvas>
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]

---

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# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
```shell
$ git checkout -b newfunc
$ # some work
$ git commit -m "Commit D"
...
$ # some work
$ git commit -m "Commit F"
```
* :warning: **issue #627 needs to be fixed**
* you create a branch to fix the issue
]

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 <canvas id='branchHowto2'></canvas>
]
]

---

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# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
```shell
$ git checkout -b newfunc
$ # some work
$ git commit -m "Commit D"
...
$ # some work
$ git commit -m "Commit F"
```
* :warning: **issue #627 needs to be fixed**
* you create a branch to fix the issue
```shell
$ git checkout master
$ git checkout -b fixit
$ # some work
$ git commit -m "Commit G"
...
$ # some work
$ git commit -m "Fixed issue #627"
```
]

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 <canvas id='branchHowto3'></canvas>
]
]

---

class: top

# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
```shell
$ git checkout -b newfunc
$ # some work
$ git commit -m "Commit D"
...
$ # some work
$ git commit -m "Commit F"
```
* :warning: **issue #627 needs to be fixed**
* you create a branch to fix the issue
```shell
$ git checkout master
$ git checkout -b fixit
$ # some work
$ git commit -m "Commit G"
...
$ # some work
$ git commit -m "Fixed issue #627"
```
* you merge your fix in `master`
]

.column[
 <canvas id='branchHowto4'></canvas>
]
]

---

class: top

# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.0**
* you start working on a new functionnality by creating a branch and commiting on it
```shell
$ git checkout -b newfunc
$ # some work
$ git commit -m "Commit D"
...
$ # some work
$ git commit -m "Commit F"
```
* :warning: **issue #627 needs to be fixed**
* you create a branch to fix the issue
```shell
$ git checkout master
$ git checkout -b fixit
$ # some work
$ git commit -m "Commit G"
...
$ # some work
$ git commit -m "Fixed issue #627"
```
* you merge your fix in `master`
```shell
$ git checkout master
$ git merge fixit
$ git tag v0.2.1 # lightweight tag
```
]

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 <canvas id='branchHowto5'></canvas>
]
]

---

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# How to use `git` branches

.row[
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* SuperProg :copyright: is in state **v0.2.1**
* you can resume working on the new functionnality
]

.column[
 <canvas id='branchHowto6'></canvas>
]
]

---

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# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.1**
* you can resume working on the new functionnality
```shell
$ git checkout newfunc
$ # some work
$ git commit -m "Commit J"
```
* when you are ready, merge the new functionnality in the `master` branch
]

.column[
 <canvas id='branchHowto7'></canvas>
]
]

---

class: top

# How to use `git` branches

.row[
.column.w45[
* SuperProg :copyright: is in state **v0.2.1**
* you can resume working on the new functionnality
```shell
$ git checkout newfunc
$ # some work
$ git commit -m "Commit J"
```
* when you are ready, merge the new functionnality in the `master` branch
```shell
$ git checkout master
$ git merge newfunc
$ git tag v0.3.0
```
]

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 <canvas id='branchHowto8'></canvas>
]
]

---

# Remote repositories

.mermaid.w70.hcenter[
    sequenceDiagram
        Remote-->>+Local repo: git clone/pull
        Local repo->>Files: git checkout
        Note over Files: Code...
        Files->>+Staged: git add/rm
        Staged->>-Local repo: git commit
        Local repo-->>-Remote: git push
]

## Create a bare repo
```shell
$ git init --bare
```

## Declare and sync from a remote repo
```shell
$ git remote add farAway http://some.domain.com/path/to/repo.git
$ git fetch farAway && git merge
$ git pull farAway
```

---

# Conclusions on `git`

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## To sum up...
* very powerful tool, can be complex sometimes
* **can work offline !**
* rock-solid, very efficient
* **decentralized !**
* several source forges are using it (`github`, `bitbucket`, `gitlab`, etc...)
* learn a few commands and start using it !
* several ways to use it, *follow the guidelines*
* **the de-facto standard CVS**

.hcenter.w50[![](images/git_logo.png)]
]
.column.w55[
<canvas id='gitExample1'></canvas>
]
]