Git for beginners: The definitive practical guide

Question

Ok, after seeing this post by PJ Hyett, I have decided to skip to the end and go with Git.

So what I need is a beginner's practical guide to Git. "Beginner" being defined as someone who knows how to handle their compiler, understands to some level what a Makefile is, and has touched source control without understanding it very well.

"Practical" being defined as this person doesn't want to get into great detail regarding what Git is doing in the background, and doesn't even care (or know) that it's distributed. Your answers might hint at the possibilities, but try to aim for the beginner that wants to keep a 'main' repository on a 'server' which is backed up and secure, and treat their local repository as merely a 'client' resource.

So:

Installation/Setup

• How to install Git
• How do you set up Git? Try to cover Linux, Windows, Mac, think 'client/server' mindset.
  • Setup GIT Server with Msysgit on Windows
• How do you create a new project/repository?
• How do you configure it to ignore files (.obj, .user, etc) that are not really part of the codebase?

Working with the code

• How do you get the latest code?
• How do you check out code?
• How do you commit changes?
• How do you see what's uncommitted, or the status of your current codebase?
• How do you destroy unwanted commits?
• How do you compare two revisions of a file, or your current file and a previous revision?
• How do you see the history of revisions to a file?
• How do you handle binary files (visio docs, for instance, or compiler environments)?
• How do you merge files changed at the "same time"?
• How do you undo (revert or reset) a commit?

Tagging, branching, releases, baselines

• How do you 'mark' 'tag' or 'release' a particular set of revisions for a particular set of files so you can always pull that one later?
• How do you pull a particular 'release'?
• How do you branch?
• How do you merge branches?
• How do you resolve conflicts and complete the merge?
• How do you merge parts of one branch into another branch?
• What is rebasing?
• How do I track remote branches?
• How can I create a branch on a remote repository?
• How do I delete a branch on a remote repository?
• Git workflow examples

Other

• Describe and link to a good GUI, IDE plugin, etc. that makes Git a non-command line resource, but please list its limitations as well as its good.
  • msysgit - Cross platform, included with Git
  • gitk - Cross platform history viewer, included with Git
  • gitnub - Mac OS X
  • gitx - Mac OS X history viewer
  • smartgit - Cross platform, commercial, beta
  • tig - console GUI for Linux
  • qgit - GUI for Windows, Linux
  • Git Extensions - package for Windows, includes friendly GUI
• Any other common tasks a beginner should know?
  • Git Status tells you what you just did, what branch you have, and other useful information
• How do I work effectively with a subversion repository set as my source control source?

Other Git beginner's references

• Git guide
• Git book
• Git magic
• gitcasts
• GitHub guides
• Git tutorial
• Progit - book by Scott Chacon
• Git - SVN Crash Course
• Git from the bottom up
• Git ready
• gitref.org
• Git visual cheatsheet

Delving into Git

• Understanding Git conceptually
• Git for computer scientists (and another version)

I will go through the entries from time to time and 'tidy' them up so they have a consistent look/feel and it's easy to scan the list - feel free to follow a simple "header - brief explanation - list of instructions - gotchas and extra info" template. I'll also link to the entries from the bullet list above so it's easy to find them later.

Answer 1

How to install Git

On Windows:

Install msysgit

There are several downloads:

• Git: Use this unless you specifically need one of the other options below.
• PortableGit: Use this if you want to run Git on a PC without installing on that PC (e.g. running Git from a USB drive)
• msysGit: Use this if you want to develop Git itself. If you just want to use Git for your source code, but don't want to edit Git's source code, you don't need this.

This also installs a Cygwin bash shell, so you can use the git in a nicer shell (than cmd.exe), and also includes git-gui (accessible via git gui command, or the Start > All Programs > Git menu)

Mac OS X

Use the git-osx-installer, or you can also install from source

Via a package manager

Install git using your native package manager. For example, on Debian (or Ubuntu):

apt-get install git-core

Or on Mac OS X, via MacPorts:

sudo port install git-core+bash_completion+doc

…or fink:

fink install git

…or Homebrew:

brew install git

On Red Hat based distributions, such as Fedora:

yum install git

In Cygwin the Git package can be found under the "devel" section

From source (Mac OS X/Linux/BSD/etc.)

In Mac OS X, if you have the Developer Tools installed, you can compile Git from source very easily. Download the latest version of Git as a .tar.bz or .tar.gz from http://git-scm.com/, and extract it (double click in Finder)

On Linux/BSD/etc. it should be much the same. For example, in Debian (and Ubuntu), you need to install the build-essential package via apt.

Then in a Terminal, cd to where you extracted the files (Running cd ~/Downloads/git*/ should work), and then run..

./configure && make && sudo make install

This will install Git into the default place (/usr/local - so git will be in /usr/local/bin/git)

It will prompt you to enter your password (for sudo), this is so it can write to the /usr/local/ directory, which can only be accessed by the "root" user so sudo is required!

If you with to install it somewhere separate (so Git's files aren't mixed in with other tools), use --prefix with the configure command:

./configure --prefix=/usr/local/gitpath
make
sudo make install

This will install the git binary into /usr/local/bin/gitpath/bin/git - so you don't have to type that every time you, you should add into your $PATH by adding the following line into your ~/.profile:

export PATH="${PATH}:/usr/local/bin/gitpath/bin/"

If you do not have sudo access, you can use --prefix=/Users/myusername/bin and install into your home directory. Remember to add ~/bin/ to $PATH

The script x-git-update-to-latest-version automates a lot of this:

This script updates my local clone of the git repo (localy at ~/work/track/git), and then configures, installs (at /usr/local/git-git describe) and updates the /usr/local/git symlink.

This way, I can have /usr/local/git/bin in my PATH and I'm always using the latest version.

The latest version of this script also installs the man pages. You need to tweak your MANPATH to include the /usr/local/git/share/man directory.

Answer 2

How do you set up a shared team repository?

How to set up a normal repository is described here -- but how do you set up a team repository that everybody can pull and push from and to?

Using a shared NFS file system

Assuming your team already has for instance a shared group membership that can be used.

mkdir /your/share/folder/project.git
cd /your/share/folder/project.git
newgrp yourteamgroup # if necessary
git init --bare --shared

To start using this repository the easiest thing to do is start from a local repository you already have been using:

cd your/local/workspace/project
git remote add origin /your/share/folder/project.git
git push origin master

Others can now clone this and start working:

cd your/local/workspace
git clone /your/share/folder/project.git

Using SSH

Set up a user account on the target server. Whether you use an account with no password, an account with a password, or use authorized_keys really depend on your required level of security. Take a look at Configuring Git over SSH for some more information.

If all developers use the same account for accessing this shared repository, you do not need to use the --shared option as above.

After initing the repository in the same way as above, you do the initial push like this:

cd your/local/workspace/project
git remote add origin user@server:/path/to/project.git
git push origin master

See the similarity with the above? The only thing that might happen in addition is SSH asking for a password if the account has a password. If you get this prompt on an account without a password the SSH server probably has disabled PermitEmptyPasswords.

Cloning now looks like this:

cd your/local/workspace
git clone user@server:/path/to/project.git

Answer 3

Commit Changes

Once you've edited a file, you need to commit your changes to git. When you execute this command it will ask for a commit message - which is just a simple bit of text that tells everyone what you've changed.

$ git commit source/main.c

Will commit the file main.c in the directory ./source/

$ git commit -a # the -a flag pulls in all modified files

will commit all changed files (but not new files, those need to be added to the index with git-add). If you want to commit only certain files then you will need to stage them first with git-add and then commit without the -a flag.

Commiting only changes your local repository though not the remote repositories. If you want to send the commits to the remote repository then you will need to do a push.

$ git push <remote> <branch> # push new commits to the <branch> on the <remote> repository

For someone coming from CVS or SVN this is a change since the commit to the central repository now requires two steps.

Answer 4

A real good paper for understanding how Git works is The Git Parable. Very recommended!

Answer 5

How do I delete a branch on a remote repository?

Perform a push in your remote using : before the name of the branch

git push origin :mybranchname

being origin the name of your remote and mybranchname the name of the branch about to be deleted

http://help.github.com/remotes/

Answer 6

Workflow example with GIT.

Git is extremely flexible and adapts good to any workflow, but not enforcing a particular workflow might have the negative effect of making it hard to understand what you can do with git beyond the linear "backup" workflow, and how useful branching can be for example.

This blog post explains nicely a very simple but effective workflow that is really easy to setup using git.

quoting from the blog post: We consider origin/master to be the main branch where the source code of HEAD always reflects a production-ready state:

The workflow has become popular enough to have made a project that implements this workflow: git-flow

Nice illustration of a simple workflow, where you make all your changes in develop, and only push to master when the code is in a production state:

Now let's say you want to work on a new feature, or on refactoring a module. You could create a new branch, what we could call a "feature" branch, something that will take some time and might break some code. Once your feature is "stable enough" and want to move it "closer" to production, you merge your feature branch into develop. When all the bugs are sorted out after the merge and your code passes all tests rock solid, you push your changes into master.

During all this process, you find a terrible security bug, that has to be fixed right away. You could have a branch called hotfixes, that make changes that are pushed quicker back into production than the normal "develop" branch.

Here you have an illustration of how this feature/hotfix/develop/production workflow might look like (well explained in the blog post, and I repeat, the blog post explains the whole process in a lot more detail and a lot better than I do.