Introduction to Git

Git Version Control

Git is a distributed version control and file management system
everyone gets his/her own copy of the project on his own computer, that means:
work offline = very fast
tracking all changes of multiple developers (modifications, adding, movings, deletions,...) and merging them

working directory
local directory of your git-project --> location of your source code / files
here you make your changes
index (cache) - Staging Area
you can not commit your changed files until you have "staged" them (add)
after staging your files (taking a kind of a snapshot), you can commit
purpose: the staging area allows you to control what you want to commit
not completed modification can left out of the commit
after committing, the staging area will be wiped
local repository
is a git-project on your local computer
by using a remote repository (e.g. GitHub), the local repository shall be an exact copy (clone) of the remote-git project (in most cases of the openETCS-project)
changes to your local files will be saved in your local repository by committing
remote repository
is a centralized git server that hosts git-projects (GitHub)
is not needed for using Git, but it is an easy way to share Git-projects to different users/developers

on windows, there are different ways to use git:
via command line (bash) (which is the recommended method to learn Git): http://git-scm.com/
or you can use graphical interfaces (GUI Clients): http://git-scm.com/download/gui/win
download and install your prefered method
while installing the program, on "Select Components" select "Simple context menu (Registry based)" --> "Git bash Here" and "Git GUI Here", that eases the handling with Git (later using the default settings is fine)
on Linux (e.g. Ubuntu):
run in command line: sudo apt-get install git

git init
the git init command initializes a new Git repository, this places a project under revision control
a (hidden) .git folder will be added, the revisions will be recorded here (contains the necessary metadata)
git init the current directory will be transformed into a Git repository
git init <directory> an empty Git Repo will be created in the specified directory
git clone
the git clone command creates a copy of an existing Git repository
git clone <repo> clone a given (also local or remote) repository onto your local machine
git clone <repo> <directory> cloning the Repo in the specified directory locally
there is no distinction between working copy and the central repository (unlike SVN) - they are all full-fledged git repositories
git config *git wants to know who you are, therefore run git bash, type the following lines and confirm each line by hitting enter:
git config --global user.name "Name"
git config --global user.email "email@example.com"
these information will be recorded with your commit/snapshot

git add
the git add command moves changes from the working directory to the staging area
this allows you to prepare a snapshot before committing your work
git add <file> [stages all changes in the for your next commit]
git add <directory> [stages in the specified ]
git commit
commits the staged snapshot, this command launches an editor (vim by default) for adding a commit message, after saving and closing the editor your commit will be be created
instead of starting an editor you can type git commit -m ""
the git commit -a command commits a snapshot of all changes in the working directory, but only those files that are added at some point in their history (git add)

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