GIT 101

Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.

Based on this article I am using GITHUB http://www.github.com for hosting my repositories securely online. Code is hosted on GITHUB makes the code easy to browse, download, fork, etc.

Clone a project

Cloning a project is creating a local copy on your host of a remote repository.

$ git clone https://github.com/vision1983/nfw.git

Joining / Fork a project

On GITHUB you can create a fork which is a copy of repository hosted on GITHUB within your own GITHUB space.

Once you pushed your changes to own copy on GITHUB you can do a pull request on GITHUB which will inform the maintainers of the original project that you wish to merge your changes upstream.

Creating your own GITHUB project

Create a repository on GITHUB without initializing.

  • Enter your source code directory
  • Create a new repository with empty README.md or README.rst.
$ git init
$ git add README.md
$ git commit -m "first commit"
$ git remote add origin https://github.com/vision1983/test.git
$ git push -u origin master

or push exisiting repository to GITHUB

git remote add origin https://github.com/vision1983/test.git
git push -u origin master

Working with local repository

To commit changes you need to stage the changes using the following commands:

Add file to repository

$ git add file

Remove file from repository

$ git del file

Before committing you can undo or checkout original file

$ git checkout file

Commit changes locally

$ git commit -a

Finally upload or push to GITHUB

$ git push

Syncing a fork

Sync a fork of a repository to keep it up-to-date with the upstream repository.

Before you can sync your fork with an upstream repository, you must configure a remote that points to the upstream repository in GITHUB.

List current configured remote repository for your fork

$ git remote -v
origin  https://github.com/YOUR_USERNAME/YOUR_FORK.git (fetch)
origin  https://github.com/YOUR_USERNAME/YOUR_FORK.git (push)

Specify a new remote upstream repository that will be synced with the fork

$ git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.

Verify the new upstream repository you've specified for your fork

$ git remote -v
origin https://github.com/YOUR_USERNAME/YOUR_FORK.git (fetch)
origin https://github.com/YOUR_USERNAME/YOUR_FORK.git (push)
upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git (fetch)
upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git (push)

Fetch the branches and their respective commits from the upstream repository. Commits to master will be stored in a local branch, upstream/master

$ git fetch upstream
remote: Counting objects: 75, done.
remote: Compressing objects: 100% (53/53), done.
remote: Total 62 (delta 27), reused 44 (delta 9)
Unpacking objects: 100% (62/62), done.
From https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY
* [new branch]      master     -> upstream/master

Check out your fork's local master branch

$ git checkout master
Switched to branch 'master'

Merge the changes from upstream/master into your local master branch. This brings your fork's master branch into sync with the upstream repository, without losing your local changes

$ git merge upstream/master

GIT Tags

Git has the ability to tag specific points in history as being important. Typically people use this functionality to mark release points (1.0.0, and so on)

List your tags

$ git tag
0.0.1
0.0.2

Git uses two main types of tags

  • lightweight
  • and annotated.

Annotated Tags

Annotated as per GIT Documentation

Annotated tags, however, are stored as full objects in the Git database. They’re checksummed; contain the tagger name, email, and date; have a tagging message; and can be signed and verified with GNU Privacy Guard (GPG). It’s generally recommended that you create annotated tags so you can have all this information; but if you want a temporary tag or for some reason don’t want to keep the other information, lightweight tags are available too.

Creating an annotated tag

The easiest way is to specify -a when you run the tag command.

$ git tag -a 0.0.2 -m "my version 0.0.2"
$ git tag
0.0.0
0.0.1
0.0.2

The -m specifies a tagging message, which is stored with the tag.

You can see the tag data along with the commit that was tagged by using the git show command

$ git show 0.0.2

Lightweight Tags

Lightweight as per GIT Documentation

A lightweight tag is very much like a branch that doesn’t change. It just points to a specific commit.

To create a lightweight tag, don’t supply the -a, -s, or -m option

$ git tag 0.0.3
$ git tag
0.0.0
0.0.1
0.0.2
0.0.3

When you run git show on the tag, you don’t see the extra tag information as per with annotated tag.

Tagging Later

You can also tag commits after you’ve moved past them.

Retrieve commit history looks like this

$ git log --pretty=oneline

Tag based on checksum from history

$ git tag -a 0.0.6 [checksum]

Sharing Tags

By default, the git push command doesn’t transfer tags to remote servers. You will have to explicitly push tags to a shared server after you have created them.

$ git push origin [tagname]

If you have a lot of tags that you want to push up at once, you can

$ git push origin --tags

Delete Tags

Delete tag locally

$ git tag -d 0.0.1

Delete tag from upstream

$ git push origin :refs/tags/1.0.5

Now, when someone else clones or pulls from your repository, they will get all your tags as well.

Managing Branches

In your GITHUB project, you need to keep your master branch clean, by clean I mean without any changes, like that you can create at any time a branch from your master. Each time, that you want to commit a bug or a feature, you need to create a branch for it, which will be a copy of your master branch.

When you do a pull request on a branch, you can continue to work on another branch and make another pull request on this other branch.

Before creating a new branch, pull the changes from upstream. Your master needs to be up to date.

Create the branch on your local machine and switch in this branch

$ git checkout -b [name_of_your_new_branch]

Push the branch on github

$ git push origin [name_of_your_new_branch]

When you want to commit something in your branch, be sure to be in your branch.

You can see all branches created by using

$ git branch

See details on branches for origin/GITHUB

$ git remote show origin

Switch to a branch

$ git checkout [name_of_your_new_branch]

Pull updates from branch on GITHUB

$ git pull origin [name_of_your_new_branch]

Push updates to your branch on GITHUB

$ git push origin [name_of_your_new_branch]

Delete a branch on your local filesystem

$ git branch -d [name_of_your_new_branch]

Force the deletion of local branch on your filesystem

$ git branch -D [name_of_your_new_branch]

Delete the branch on github

$ git push origin :[name_of_your_new_branch]