Fake git man page generator
This manual is designed to be readable by someone with basic UNIX command-line skills, but no previous knowledge of Git. People needing to do actual development will also want to read Developing with Git and Sharing development with others. Comprehensive reference documentation is available through the man pages, or git-help command. With the latter, you can use the manual viewer of your choice; see git-help for more information.SEE VIDEO BY TOPIC: How to Setup Github Pages - Website on Github - Complete Beginner Tutorial
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This manual is designed to be readable by someone with basic UNIX command-line skills, but no previous knowledge of Git. People needing to do actual development will also want to read Developing with Git and Sharing development with others.
Comprehensive reference documentation is available through the man pages, or git-help command. With the latter, you can use the manual viewer of your choice; see git-help for more information. See also Git Quick Reference for a brief overview of Git commands, without any explanation. Finally, see Notes and todo list for this manual for ways that you can help make this manual more complete. The best way to get one is by using the git-clone command to download a copy of an existing repository.
The initial clone may be time-consuming for a large project, but you will only need to clone once. The clone command creates a new directory named after the project git or linux in the examples above. After you cd into this directory, you will see that it contains a copy of the project files, called the working tree , together with a special top-level directory named.
Git is best thought of as a tool for storing the history of a collection of files. In Git each such version is called a commit. A single Git repository can track development on multiple branches.
It does this by keeping a list of heads which reference the latest commit on each branch; the git-branch command shows you the list of branch heads:. A freshly cloned repository contains a single branch head, by default named "master", with the working directory initialized to the state of the project referred to by that branch head.
Most projects also use tags. Tags are expected to always point at the same version of a project, while heads are expected to advance as development progresses. Create a new branch head pointing to one of these versions and check it out using git-switch :. The working directory then reflects the contents that the project had when it was tagged v2. Note that if the current branch head was your only reference to a particular point in history, then resetting that branch may leave you with no way to find the history it used to point to; so use this command carefully.
Every change in the history of a project is represented by a commit. The git-show command shows the most recent commit on the current branch:. Every commit has a hexdigit id, sometimes called the "object name" or the "SHA-1 id", shown on the first line of the git show output. You can usually refer to a commit by a shorter name, such as a tag or a branch name, but this longer name can also be useful.
Most importantly, it is a globally unique name for this commit: so if you tell somebody else the object name for example in email , then you are guaranteed that name will refer to the same commit in their repository that it does in yours assuming their repository has that commit at all.
Since the object name is computed as a hash over the contents of the commit, you are guaranteed that the commit can never change without its name also changing. In fact, in Git concepts we shall see that everything stored in Git history, including file data and directory contents, is stored in an object with a name that is a hash of its contents. Every commit except the very first commit in a project also has a parent commit which shows what happened before this commit. Following the chain of parents will eventually take you back to the beginning of the project.
However, the commits do not form a simple list; Git allows lines of development to diverge and then reconverge, and the point where two lines of development reconverge is called a "merge". The commit representing a merge can therefore have more than one parent, with each parent representing the most recent commit on one of the lines of development leading to that point.
The best way to see how this works is using the gitk command; running gitk now on a Git repository and looking for merge commits will help understand how Git organizes history. In the following, we say that commit X is "reachable" from commit Y if commit X is an ancestor of commit Y. Equivalently, you could say that Y is a descendant of X, or that there is a chain of parents leading from commit Y to commit X.
We will sometimes represent Git history using diagrams like the one below. Time goes left to right:. If we need to talk about a particular commit, the character "o" may be replaced with another letter or number.
When we need to be precise, we will use the word "branch" to mean a line of development, and "branch head" or just "head" to mean a reference to the most recent commit on a branch. In the example above, the branch head named "A" is a pointer to one particular commit, but we refer to the line of three commits leading up to that point as all being part of "branch A".
However, when no confusion will result, we often just use the term "branch" both for branches and for branch heads. The special symbol "HEAD" can always be used to refer to the current branch. The git switch command normally expects a branch head, but will also accept an arbitrary commit when invoked with --detach; for example, you can check out the commit referenced by a tag:.
This is an easy way to check out a particular version without having to make up a name for the new branch. You can still create a new branch or tag for this version later if you decide to. The "master" branch that was created at the time you cloned is a copy of the HEAD in the repository that you cloned from. That repository may also have had other branches, though, and your local repository keeps branches which track each of those remote branches, called remote-tracking branches, which you can view using the -r option to git-branch :.
In this example, "origin" is called a remote repository, or "remote" for short. The branches of this repository are called "remote branches" from our point of view. The remote-tracking branches listed above were created based on the remote branches at clone time and will be updated by git fetch hence git pull and git push. See Updating a repository with git fetch for details. You might want to build on one of these remote-tracking branches on a branch of your own, just as you would for a tag:.
See detached head. Note that the name "origin" is just the name that Git uses by default to refer to the repository that you cloned from. Branches, remote-tracking branches, and tags are all references to commits. The full name is occasionally useful if, for example, there ever exists a tag and a branch with the same name. Newly created refs are actually stored in the.
However, for efficiency reasons they may also be packed together in a single file; see git-pack-refs. As another useful shortcut, the "HEAD" of a repository can be referred to just using the name of that repository. So, for example, "origin" is usually a shortcut for the HEAD branch in the repository "origin".
After you clone a repository and commit a few changes of your own, you may wish to check the original repository for updates. The git-fetch command, with no arguments, will update all of the remote-tracking branches to the latest version found in the original repository. You can also track branches from repositories other than the one you cloned from, using git-remote :. New remote-tracking branches will be stored under the shorthand name that you gave git remote add , in this case staging :.
It does this by storing compressed snapshots of the contents of a file hierarchy, together with "commits" which show the relationships between these snapshots. We start with one specialized tool that is useful for finding the commit that introduced a bug into a project.
Suppose version 2. The git-bisect command can help you do this:. HEAD is now detached from any branch and points directly to a commit with commit id that is reachable from "master" but not from v2. Compile and test it, and see whether it crashes. Assume it does crash. Continue like this, telling Git at each stage whether the version it gives you is good or bad, and notice that the number of revisions left to test is cut approximately in half each time.
After about 13 tests in this case , it will output the commit id of the guilty commit. You can then examine the commit with git-show , find out who wrote it, and mail them your bug report with the commit id.
Finally, run. For example, occasionally you may land on a commit that broke something unrelated; run. Choose a safe-looking commit nearby, note its commit id, and check it out with:. Instead of git bisect visualize and then git reset --hard fb47ddb2db , you might just want to tell Git that you want to skip the current commit:. In this case, though, Git may not eventually be able to tell the first bad one between some first skipped commits and a later bad commit.
There are also ways to automate the bisecting process if you have a test script that can tell a good from a bad commit. See git-bisect for more information about this and other git bisect features. Some examples:. For example, if you run git fetch without specifying a local branch as the target of the operation. The git-rev-parse command is a low-level command that is occasionally useful for translating some name for a commit to the object name for that commit:.
This creates a "lightweight" tag. If you would also like to include a comment with the tag, and possibly sign it cryptographically, then you should create a tag object instead; see the git-tag man page for details. The git-log command can show lists of commits. On its own, it shows all commits reachable from the parent commit; but you can also make more specific requests:.
And of course you can combine all of these; the following finds commits since v2. See the --pretty option in the git-log man page for more display options. Note that git log starts with the most recent commit and works backwards through the parents; however, since Git history can contain multiple independent lines of development, the particular order that commits are listed in may be somewhat arbitrary.
That will produce the diff between the tips of the two branches. Sometimes what you want instead is a set of patches; for this you can use git-format-patch :. You can always view an old version of a file by just checking out the correct revision first. But sometimes it is more convenient to be able to view an old version of a single file without checking anything out; this command does that:. Before the colon may be anything that names a commit, and after it may be any path to a file tracked by Git.
You could compare the object names:. Or you could recall that the Suppose you know that the commit e05db0fd fixed a certain problem. The git-describe command does the opposite, naming the revision using a tag on which the given commit is based:.
Introduction to Git
GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again. Go back.
This page provides some GIT "best practices" based upon the experiences of the page's author. I welcome suggestions from other GIT users to help improve this page and to learn other ways to use GIT which is a very useful, albeit complicated, tool. Some helpful links to GIT resources:. During development, a project's state changes: files are added or removed, registered files get modified, etc. At certain points you decide the current state should be saved, which is when you commit the changes to the repository.
Git is a way to store, back up and organise your code. You are working on a software project. As your project grows, and you work on it together with other people, you will need some way of:. Git can do all these things. It takes a bit of getting used to, but it pays off to learn the basics of Git once and then use it again and again. Some students even keep a git repository for every unit they take so they can keep track of all their work. Git is not the only system that can do this, but it is the most popular one by far and knowing Git is pretty much a requirement for lots of technical job interviews as a developer. So you might as well learn Git. The aim of this tutorial is to get you to the point where you can use Git productively, and understand some of these manuals if you need to. If you need to install it yourself:.