So, what is Git in a nutshell? This is an important section to absorb, because if you understand what Git is and the fundamentals of how it works, then using Git. The second edition of this book is meant to address those example of Git hosting, I have decided to turn that part of the book into more. Access this book for free. ISBN ; This book is an open access book, you can download it for free on Softcover 44,95 €.
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When you do actions in Git, nearly all of them only add data to the Git database. You modify files in your working tree. The working tree is a single checkout of one version of the project.
1.3 Getting Started – Git Basics
Modified means that you have changed the file but have not committed it to your database yet. This is the most important part of Git, and it is what is copied when you clone a repository from another computer.
So, what is Git in a nutshell? The major difference between Git and any other VCS Subversion and friends included is the way Git thinks about its data. The staging area is a file, generally contained in your Git directory, that stores information about what will go into your next commit.
Embedding Git in your Applications A2. Git is a member of Software Freedom Conservancy, which handles legal and financial needs for the project. Git in Other Environments A1. This is an important section to absorb, because if you understand what Git is and the fundamentals of how it works, then using Git effectively will probably be much easier for you.
Git has three main states that your files can reside in: It makes Git reconsider almost every aspect of version control that most other systems copied from the previous generation. This may not seem like a huge deal, but you may be surprised what a big difference it can make. Committed means that the data is safely stored in your local database.
For a more in-depth look at how Git stores its data and how you can recover data that seems lost, see Undoing Things.
The Git directory is where Git stores the metadata and object database for your project. In many other systems, doing so is either impossible or painful. If it has been modified and was added to the staging area, it is staged. This leads us to the three main sections of a Git project: Git and Other Systems 9. A SHA-1 hash looks something like this:.
And if it was changed since it was checked out but has not been staged, it is modified. This is a character string composed of hexadecimal characters 0—9 and a—f and calculated based on the contents of a file or directory structure in Git. With Git, every time you commit, or save the state of your project, Git basically takes a picture of what all your files look like at that moment and stores a reference to that snapshot.
You will see these hash values all over the place in Git because it uses boo so much. Git on the Server 4. gtipro
Git thinks about its data more like a stream of snapshots. These other systems CVS, Subversion, Perforce, Bazaar, and so on think of the information they store as a set of files and the changes made to each file over time this is commonly described as delta-based version control. Conceptually, most other systems store information as a list of file-based changes.
You do a commit, which takes the files as they are in the staging area and stores that snapshot permanently to your Git directory. The mechanism that Git uses for this checksumming is called a SHA-1 hash. This functionality is built into Git at the lowest levels and is integral to its philosophy. Instead, Git thinks of its data more like a series of snapshots of a miniature filesystem. Because you have the gitpfo history of the project right there on your local disk, most operations seem almost instantaneous.
This is an important distinction between Git and nearly all other VCSs. You selectively stage just those changes you want to be part of your next commit, which adds only those changes to the staging area.
Git – Git Basics
This makes using Git a joy because we know we can experiment without the danger of severely screwing things up. This means you see the project history almost instantly.
This makes Git more like a mini filesystem with some incredibly powerful tools built on top of it, rather than simply a VCS. Everything in Git is checksummed before it is stored and is then referred to by that checksum.
If you want to see the changes introduced between the current version of a file and the file a month ago, Git can look up the file a month ago and do a local difference calculation, instead of having to either ask a remote server to do it or pull an older version of the file from the remote server to do it locally. These files are pulled out of the compressed database in the Git directory and placed on disk for you to use or modify.
If you get on an yitpro or a train and want to do a little work, you can commit happily to your local copy, remember? Git Has Integrity Everything in Git is checksummed before it is stored and is then referred to by that checksum.
Pro Git, Second Edition
Consider becoming a supporter! It is hard to get the system to do anything that is not undoable or to make it erase data in any way. Staged means that you have marked a modified file in its current version to go into your next commit snapshot. In fact, Git stores everything in its database not by file name but by the hash value of its contents. Conservancy is currently raising funds to continue their mission.