Praktische Aspekte der Informatik - graphics.tu-bs.de · Git Basics Initial checkout, and regular update to the newest version: git init / git clone / git pull Make changes:

Praktische Aspekte

der InformatikMoritz Mühlhausen

Prof. Marcus Magnor

https://graphics.tu-bs.de/teaching/ss19/padi/

Software VersioningGit basics, workflow, and commands


Further Reading

Warning!The following slides are meant to give you

a very superficial introduction.

If you want to learn more, have a look at:

http://git-scm.com


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


A simple file server


Lock-modify-unlock


Copy-modify-merge


Copy-modify-merge


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Git Basics

• Benefits:

Global revision numbers

No serialization (parallel editing)

Offline editing

Merging works most of the time

• Drawbacks:

Requires a disciplined workflow and maintenance!


Git Basics

Initial checkout, and regular update to the newest version:

git init / git clone <url> / git pull

Make changes:

git add <files> / git mv <src> <dst>

Examine your changes:

git status / git diff [file]

Possibly undo some changes:

git reset [file] / git checkout --<file>

Commit changes:

git commit / git push


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Git Setup

Start versioning with init command:

$ git init

Initialized empty Git repository in ...

Creates an empty git repository with no remote target

• Pure versioning, no backup function

Add remote targets with remote add command

$ git remote add <name> <url>

Now push/pull commands with target <name> will access the

given repository

• If it is a repository and you have access to it


Git Setup

Clone an already existing repository the long way:

$ git init

$ git remote add origin <url>

$ git branch ––set-upstream-to=origin/master master

$ git pull

Or use the clone shortcut

$ git clone <url>

Creates a subfolder with the repository name and sets everything up


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Git Workflow

Always use the pull command to get the latest version:

$ git pull

Updating 7073847..a005fe8

Fast-forward

food/sandwich.h | 2 +-

food/sandwich.cpp | 6 +++++-

2 files changed, 6 insertions(+), 2 deletions(-)

For bug hunting it is useful to look at old revisions by adding

$ git checkout <commit>

$ git blame <file>

$ git bisect


Git Workflow

Check the status of all local files compared to the repository:

$ git status

Changes to be committed:

modified: food/sandwich.h

Changes not staged for commit:

modified: food/sandwich.cpp

Untracked files:

food/food.txt


Git Workflow

$ git diff

index: 05f23b8..800e28a 100644

--- a/food/sandwich.cpp

+++ b/food/sandwich.cpp

@@ -1,5 +1,9 @@

#include "sandwich.h"

+#include <sys/types.h>

+#include <sys/stat.h>

+#include <unistd.h>

+#include <stdio.h>

int main(void) {

- printf("Sixty-four slices of American Cheese...\n");

+ printf("Sixty-five slices of American Cheese...\n");

}


Git Workflow

If there is a conflict, all relevant versions are still available in their

respective commit:

$ git pull

From http://git.cg.cs.tu-bs.de:6000/PADI/test

fbb93f8..f82df1b master -> origin/master

Auto-merging food/food.txt

CONFLICT (content): Merge conflict in food/food.txt

Automatic merge failed; fix conflicts and then commit the

result


Git Workflow

$ cat sandwich.txt

Top piece of bread

Mayonnaise

Lettuce

Tomato

Provolone

<<<<<<< HEAD

Salami

Mortadella

Prosciutto

=======

Sauerkraut

Grilled Chicken

>>>>>>> f82df1b22544bf943520a7669991f88b443fa81d

Creole Mustard

Bottom piece of bread


Git Workflow

You can manually merge those files:

• In editor by hand, remove the <<<, ===, >>> lines and merge them to

your desire

• Use $ git mergetool food/food.txt

You can avoid them beforehand:

$ git pull –s ours sandwich.txt

Always prefer your file over the current revision.


Git Workflow

You can then commit your merge:

$ git commit -a

Merge branch ‘master’ of http://git.cg.cs.tu-bs.de:6000/PADI/test

# Conflicts:

# food/food.txt

#

# It looks like you may be committing a merge.

# If this is not correct, please remove the file

# .git/MERGE_HEAD

# and try again

…


http://git.cg.cs.tu-bs.de:6000/PADI/test

Things to watch out for

• Commit often

• Always use understandable messages

• Only commit code that compiles

• Avoid conflicts early, by designating responsibilities.

• Do not commit temporary files!

• Do not commit ‘backup’ files!


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Git Branches

A branch refers to a separate development line in your git

repository

• Work on a specific taks without messing the main line

• Easy switching in between

A single branch log example:


Git Branches

Now you want to test something but don’t mess with the master

code

• Create a new branch

• Work on that branch and merge it later

A two branch log example:


Git Branches

Create a branch / delete a branch

$ git branch <name> / git branch –d <name>

Switch to a different branch

$ git checkout <name>

Merge a branch into the current branch

$ git merge <name>


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Git Config

Customize your git with several configuration options

$ git config <key> <setting>

Sets a config locally for this repository

For global options add --global

$ git config –-global <key> <setting>

Sets the global config which will be used if no local option is set


Git Config – First time git setup

Some options should be set globally once for each computer

Set your identity – important because git commit uses these

information

$ git config -–global user.name “<your_name>”

$ git config –-global user.email “<your_email>”

Set the editor for commit messages

$ git config –-global core.editor <editor>

If not set it uses the shell environment variables VISUAL or EDITOR

Otherwise it uses vi


Git Config – Our git problems

Unfortunately, our git certificate is self signed, so git is quite

unhappy

$ git config http.sslVerify false


Outline

What is versioning

Git Basics

Git Setup

Git Workflow

Git Branches

Git Config

Assignment


Assignment

A. Get a git account on our server

Get your account information from me.

Go to the website: git.cg.cs.tu-bs.de

Check your account.

B. Add a SSH key to your accountOptional: Create a new ssh key for your computerssh-keygen -t rsa -b 4096 -C "[email protected]”

Go to your settings -> SSH Keys

Add your key.


git.cg.cs.tu-bs.de

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Praktische Aspekte der Informatik - graphics.tu-bs.de · Git Basics Initial checkout, and regular update to the newest version: git init / git clone / git pull Make changes: