Most of the time, you will start using a Subversion repository by performing a checkout of your project. Checking out a directory from a repository creates a working copy of that directory on your local machine. Unless otherwise specified, this copy contains the youngest (that is, most recently created or modified) versions of the directory and its children found in the Subversion repository:

$ svn checkout http://svn.example.com/svn/repo/trunk
A    trunk/README
A    trunk/INSTALL
A    trunk/src/main.c
A    trunk/src/header.h
…
Checked out revision 8810.
$

Although the preceding example checks out the trunk directory, you can just as easily check out a deeper subdirectory of a repository by specifying that subdirectory's URL as the checkout URL:

$ svn checkout http://svn.example.com/svn/repo/trunk/src
A    src/main.c
A    src/header.h
A    src/lib/helpers.c
…
Checked out revision 8810.
$

Since Subversion uses a copy-modify-merge model instead of lock-modify-unlock (see 第 1.3 节 “版本模型”), you can immediately make changes to the files and directories in your working copy. Your working copy is just like any other collection of files and directories on your system. You can edit the files inside it, rename it, even delete the entire working copy and forget about it.

	警告
	因为你的工作副本“同你系统上的文件和目录没有任何区别”，你可以随意修改文件，但是你必须告诉 Subversion 你做的其他任何事。例如，你希望拷贝或移动工作副本的一个文件，你应该使用 svn copy 或者 svn move，而不要使用操作系统的拷贝移动命令，我们会在本章后面详细介绍。

除非你准备好了提交一个新文件或目录，或改变了已存在的，否则没有必要通知Subversion你做了什么。

Notice that in the previous pair of examples, Subversion chose to create a working copy in a directory named for the final component of the checkout URL. This occurs only as a convenience to the user when the checkout URL is the only bit of information provided to the svn checkout command. Subversion's command-line client gives you additional flexibility, though, allowing you to optionally specify the local directory name that Subversion should use for the working copy it creates. For example:

$ svn checkout http://svn.example.com/svn/repo/trunk my-working-copy
A    my-working-copy/README
A    my-working-copy/INSTALL
A    my-working-copy/src/main.c
A    my-working-copy/src/header.h
…
Checked out revision 8810.
$

If the local directory you specify doesn't yet exist, that's okay—svn checkout will create it for you.