S2 Version Control Systems

8/17/2019 S2 Version Control Systems

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Version Control SystemsYury Yineth Niño Roa

[email protected]

Software Engineering 2

UNIVERSIDAD NACIONAL DE COLOMBIA

mailto:[email protected]:[email protected]


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Content

• Version Control Systems

• Git Basics

• Installing Git

• Getting a Git repository

• Recording changes to the repository

• Viewing the commit history

• Branching and Merging



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What is Version Control System[VCS]?



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Background [VCS]

• [VCS] is a system that records the changes of a fileor set of files over time.

•

A [VCS] allows: – Revert files back to a previous state.

– Revert the entire project back to a previous state.

– Review changes made over time.

– See who last modified something.

• There are 3 types of [VCSs].



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What are the types of [VCSs]?



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Types of [VCSs]

• Before [VCSs]

The method of many people to control versions wasto copy files into a directory by each version.


Where is the

last version?


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Types of [VCSs]

• Local [VCSs]

These systems had a simple database that kept all thechanges to files under revision control.


[BOOK] ProGit


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Types of [VCSs]

• Centralized [VCSs]

These systems have a single server that contains allthe versioned files and a number of clients that check

out files from that central place.


[BOOK] ProGit


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Types of [VCSs]

• Distributed [VCSs]

In these systems the clients don’t just check out thelatest snapshot of the files, they fully mirror the

repository.


[BOOK] ProGit


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I don’t understand several terms



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Terminology


Term Description

RepositoryContains the history, versions over time, branches andtags.Each copy of the repository is a complete repository.

Workingtree

Contains the content of a commit which you cancheckout.

Branch Is a separate code line with its own history.

One of the branches is the default (master).

Tag Points to a commit which uniquely identifies a version

of the repository.

[URL] http://www.vogella.com/articles/Git/article.html


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Terminology


Term Description

CommitAn user commit his changes into a repository.A new commit uniquely identifies a new revision ofthe repository.

URL An URL determines the location of the repository.

Revision Represents a version of the source code.

HEAD Is a pointer to the currently selected commit object

[URL] http://www.vogella.com/articles/Git/article.html


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How does Git work?



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Git


Other

systems

Git

[BOOK] ProGit

[BOOK] ProGit


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Git Features

• Nearly every operation is local.

• Git has Integrity.

• Git generally onlyadds data.

• The 3 states:

– Modified – Staged

– C0mmitted


[BOOK] ProGit


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Git Features

• A Git workflow like this:

– A user modifies files in the working directory.

– A user stages the files.

– A user does a commit.

– If it was changed since it was checked out but has notbeen staged – Modified.

– If a file is modified but has been added to the stagingarea – Staged.

– If a version of a file is in the Git directory – Committed.



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Installing Git

• http://git-scm.com/book/en/Getting-Started-Installing-Git#Installing-from-Source

•

On Linux – $ apt-get install git

• On Windows – Download the installer .exe file from the GitHub page and

run it:

http://msysgit.github.com/


http://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://msysgit.github.com/http://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Githttp://git-scm.com/book/en/Getting-Started-Installing-Git


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First-Time Git Setup

• Checking your settings$ git config –list

• Setting your identity$ git config --global user.name “Yury“

$ git config --global user.email [email protected]

• Choose diff tool$ git config --global merge.tool vimdiff

You can choose kdiff3, tkdiff, meld, xxdiff, emerge, vimdiff, gvimdiff,ecmerge, and opendiff as ddiff tool.


mailto:[email protected]:[email protected]


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Getting a Git Repository

• There are 2 approaches: – Take an existing directory and import it into Git.

– Clone an existing Git repository from another server.

• Initializing a repository in an existing directory$ git init

$ git add .

$ git commit -m „initial project version‟

• Cloning an existing repository$ git clone git://github.com/davidmr/scio.git



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How to register changes?



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Register Changes


• Background file status

[BOOK] ProGit


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Class Exercise


1. When you first clone a repository, what is thestate of all files?

2. When you add a file to workingcopy, what is the state of this file?

3. When you edit a tracked file, what is the state ofthis file?


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Register Changes


• Checking the status of files$ git status# On branch master nothing to commit(working directory clean)

• If README is added$ git status# On branch master# Untracked files:# (use "git add ..." to include in what will

be committed)## README nothing added to commit but untracked

files present (use "git add" to track)


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Register Changes


• Tracking new files$ git add README

• If run status again$ git status# On branch master

# Changes to be committed:

# (use "git reset HEAD ..." to unstage)

#

# new file: README#


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Register Changes


• Viewing staged and unstaged changes

[BOOK] ProGit


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Register Changes


• Committing changes$ git commit – m “a message”

$ git commit -m "Story 182: Fix“

[master]: created 463dc4f: “Fix“2 files changed, 3 insertions(+), 0 deletions(-)create mode 100644 README

•

You can see in the output commit: – Which branch you committed to (master).

– What SHA-1 checksum the commit has (463dc4f).

– How many files were changed.


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Register Changes


• Removing files$ git rm [file]

• The file is only removed from the working directory:$ git rm README.txt

$ git status

# On branch master

# Changes not staged for commit:# (use "git add/rm ..." to update what

will be committed)

# deleted: README.txt


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How to view the commithistory?



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Viewing the Commit History

• The most basic and powerful tool to do this is:$ git log


[BOOK] ProGit


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Viewing the Commit History


• Using Gitk or Git GUI


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I want to be able to collaborateon any Git project? Is it possible?



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Working with Remotes

• Remote repositories are versions of the project thatare hosted on the Internet or network somewhere.

• Collaborating with others involves managing these

remote repositories, pushing and pulling data to andfrom them.

• Showing remotes

git remote

• Adding remotesgit remote add [shortname] [url]



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Working with Remotes

• Fetching to remotes$ git fetch [remote-name]

fetch command doesn’t automatically merge local work with the

remote. It’s necessary to merge manually.

$ git pull [remote-name]

• Pushing to remotes$ git push [remote-name] [branch-name]



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Is possible tagging releases inGit?

Because in SVN is possible



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Tagging

• Git has the ability to tag specific points in history asbeing important.


• Listing tags$ git tag

v0.1

v1.3

•

Lightweight tags$ git tag v1.4-lw

• Creating Tags

– Lightweight

– Annotated

•

Annotated tags$ git tag -a v1.4-m 'my version 1.4‟


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Before we finish, Can we reviewbranching?



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Git Branching

• Branching is a mechanism to diverge from the mainline of development and continue to do work.

•

When a user commit, Git stores a object with: – A pointer to the snapshot of the content staged.

– The author and message metadata.

– Zero or more pointers to the commit or commits that

were the direct parents of this commit.



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Git Branching


• Let’s assume that we have a directory containingthree files, and we stage them all and commit.

[BOOK] ProGit


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Git Branching


• After two more commits the history might looksomething like as:

[BOOK] ProGit


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What happens if we create anew branch?



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Git Branching


• $ git branch testing

$ git checkout testing

• A shorthand$ git checkout -b testing

[BOOK] ProGit


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Git Branching


• $ vim test.rb

$ git commit -a -m 'made a change'

$ git checkout master

[BOOK] ProGit


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Class Exercise


1. What happen if we make a few changes andcommit again?

[BOOK] ProGit


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Solution Exercise


[BOOK] ProGit


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Class Exercise


1. Define the commands necessary to nextworkflow:

1. Clone a project that is hosting in

git://github.com/yyninor/myweb.git2. Do work on a web site.

3. Publish these changes in the remote.

4. Create a branch for a new story you’ll working on.

5. Do some work in that branch.6. Publish these changes in your local repository.


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Solution


[BOOK] ProGit


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Creating new branch hotfix


[BOOK] ProGit

• Suppose that we have to create a new branchhotfix from master.


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Merging

• Suppose that after hotfix is tested, we want tomerge hotfix to master.


[BOOK] ProGit


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Merging

• Remember iss53 branch. Suppose we’ve decidedthat our iss53 work is complete and ready to bemerged into the master branch.

What is the difference


Vs


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Merging



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Hosting SD Services

GitHub is a web – based hostingservice for software developmentprojects that use the Git revision

control system.Google Code is Google's site for

developer tools, APIs and technicalresources.

SourceForge is a web-based sourcecode repository.



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Assignment 5

• Choose a VCS to develop your project and publishhow to clone the repository in the versioningsection of your project page.

• Read Section 5.1 of the ProGit Book, because nextwe will make a quiz about this topic.

• Decide what workflow are you going

to use within your project. Justify

your answer in the versioning section.

S2 Version Control Systems

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