git 使用入门篇

最近准备给同事培训git，发现了一个不错的资源，在这里：http://www.gitguys.com/topics/creating-a-shared-repository-users-sharing-the-repository/

原文如下，有空再译：

ommands discussed in this section:

• git init –bare
• git clone
• git remote
• git pull
• git push

Scenario: Example Remote Repository

Let’s set up our own little “remote” repository and then share it. (The repository will be “remote” to the users sharing it.)

In these examples, the other users sharing the repository will not be very remote since the repository will be on the same disk as the users’ home directories. But the git workflow and commands are identical, whether the users and repositories are just a few millimeters away on the same disk, or on a remote network across the world.

Creating The Shared Repository

We’ll have the repository created by the user gitadmin. The gitadmin‘s repository will be be the repository where everybody on the project both publishes their work and also retrieves the latest work done by others.

The scenario:

• gitadmin will create a repository.
• Other users, like Amy and Zack will then get (“git clone”) copies of gitadmin‘s remote repository.
• Changes will be pulled and pushed to and from gitadmin‘s repository.

Create Shared Repositories “Bare”

If you are creating a git repository for only your own use on projects or days when you just don’t feel like sharing, you type:

gitadmin$ git init project1
Initialized empty Git repository in /home/gitadmin/project1/.git/

However, if you are creating a git repository for sharing with git clone/pull/fetch/push, Use the –bare option to git init:

gitadmin$ git init --bare project1.git
Initialized empty Git repository in /home/gitadmin/project1.git/

If you want to know why, see Shared Repositories Should Be Bare Repositories.

Bare Repositories End in “.git”

You might have noticed the –bare repository created above ended in .git. By convention, bare git repositories should end in .git. For example, project1.git or usplash.git, etc. The .git ending of a directory signals to others that the git repository is bare.

Amy is ready to add to the remote repository

In our example, since Amy’s name begins with the first letter of the alphabet, she gets to work on the repository first.

Amy clones it:

amy$ git clone file:///home/gitadmin/project1.git
Initialized empty Git repository in /home/amy/project1/.git/
warning: You appear to have cloned an empty repository.

Git just told us the repository that Amy just cloned is empty.

We can now start creating files and publishing (“git push“) them to the shared repository.

Amy wants to see if there are any branches in the repository she just retrieved/cloned:

amy$ cd project1
amy$ git branch
amy$

The empty output from the git branch command showed are no branches in the new repository.

Amy creates her first file and commit’s the new file to the repository.

amy$ echo The beginnings of project1 > amy.file
amy$ git add .
amy$ git commit -m"Amy's initial commit"
[master (root-commit) 01d7520] Amy's initial commit
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 amy.file
amy$ git branch
* master

The cloned, bare repository didn’t have any branches, not even the master repository. When Amy did the first git commit, the master branch was created in Amy’s local repository.

Amy tries to publish her local repository to the remote repository:

amy$ git push
No refs in common and none specified; doing nothing.
Perhaps you should specify a branch such as 'master'.
fatal: The remote end hung up unexpectedly
error: failed to push some refs to 'file:///home/gitadmin/project1.git'

Oops, that didn’t work. The above happens on brand new, completely empty, branchless repositories (immediately after doing the git init –bare …).

Amy’s local repository created the master branch, but the shared repository that gitadmin created does not have any branches on it still.

Amy will take git’s advice and tell git the name of the branch she wants pushed to which remote repository. She must specify both the remote repository name and branch name.

What are the branch and repository names? Amy has been distracted lately and forgot the name of remote repository, so she’ll use the git remote command to list the names of her remote repositories:

amy$ git remote
origin

She is shown there is only one remote repository named origin. The default remote repository when you git clone a repository is named origin, so the above output isn’t surprising.

Similarly, Amy can find out the branch name in her local repository by using the git branch command:

amy$ git branch
* master

The branch name master isn’t surprising either, since master is the default branch name for git.

Armed with the remote repository name (origin) and local branch name (master) Amy can now push (publish) the changes.

The git push syntax is:
git push [remote-repository-name] [branch-or-commit-name].
Amy will push the branch named master to the remote repository named origin:

amy$ git push origin master
Counting objects: 3, done.
Writing objects: 100% (3/3), 245 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
To file:///home/gitadmin/project1.git
 * [new branch]      master -> master

The last line above reports a new branch was created: the master branch (referred to in some places as the “source”) on the local repository was mapped to the master branch (referred to in some places as the “destination”) on the remote repository.

Amy will no longer need to type git push origin master, but will be able to type git push, since the master branch now exists on the remote repository named origin:

amy$ git push
Everything up-to-date

Zack wants to play too

Now it’s Zack’s turn to play with the repository. He clones it:

zack$ git clone file:///home/gitadmin/project1.git
Initialized empty Git repository in /home/zack/project1/.git/
remote: Counting objects: 3, done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (3/3), done.
zack$ ls
amy.file

Above, the file Amy added, amy.file is copied from the shared repository to Zack’s working directory.

Zack adds a file and pushes it up to the shared repository:

zack$ cd project1
zack$ echo I am zack > zack.file
zack$ git add .
zack$ git commit -m 'zack initial commit'
[master 05affb3] zack initial commit
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 zack.file
zack$ git push
Counting objects: 4, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 283 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
To file:///home/gitadmin/project1.git
   01d7520..05affb3  master -> master

Note that Zack didn’t have to do the git push origin master to create the master branch on the remote repository, since Amy had already created the master branch on the remote repository.

Amy wants to get the latest

amy$ git pull
remote: Counting objects: 4, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From file:///home/gitadmin/project1
   01d7520..05affb3  master     -> origin/master
Updating 01d7520..05affb3
Fast-forward
 zack.file |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 zack.file
amy$ ls
amy.file  zack.file

Things are working pretty well: Amy and Zack are sharing nicely: They are contributing to (“git push“) and receiving from (“git pull“) the shared repository.

The above summarizes how to get moving with shared, remote repostitories. But there’s a lot more fun you can have with remote repositories.