Some people have trouble absorbing a new technology by reading the sort of “top down” approach provided by this book. This section is a very short introduction to Subversion, and is designed to give “bottom up” learners a fighting chance. If you prefer to learn by experimentation, the following demonstration will get you up and running. Along the way, we give links to the relevant chapters of this book.

If you're new to the entire concept of version control or to the “copy-modify-merge” model used by both CVS and Subversion, then you should read Chapter 2, Basic Concepts before going any further.

Subversion stores all versioned data in a central repository. To begin, create a new repository:

$ svnadmin create /path/to/repos
$ ls /path/to/repos
conf/  dav/  db/  format  hooks/  locks/  README.txt

This command creates a new directory /path/to/repos which contains a Subversion repository. This new directory contains (among other things) a collection of database files. You won't see your versioned files if you peek inside. For more information about repository creation and maintenance, see Chapter 5, Repository Administration.

Subversion has no concept of a “project”. The repository is just a virtual versioned filesystem, a large tree that can hold anything you wish. Some administrators prefer to store only one project in a repository, and others prefer to store multiple projects in a repository by placing them into separate directories. The merits of each approach are discussed in the section called “Choosing a Repository Layout”. Either way, the repository only manages files and directories, so it's up to humans to interpret particular directories as “projects”. So while you might see references to projects throughout this book, keep in mind that we're only ever talking about some directory (or collection of directories) in the repository.

In this example, we assume that you already have some sort of project (a collection of files and directories) that you wish to import into your newly created Subversion repository. Begin by organizing them into a single directory called myproject (or whatever you wish). For reasons that will be clear later (see Chapter 4, Branching and Merging), your project's tree structure should contain three top-level directories named branches, tags, and trunk. The trunk directory should contain all of your data, while branches and tags directories are empty:

/tmp/myproject/branches/
/tmp/myproject/tags/
/tmp/myproject/trunk/
                     foo.c
                     bar.c
                     Makefile
                     …

The branches, tags, and trunk subdirectories aren't actually required by Subversion. They're merely a popular convention that you'll most likely want to use later on.

Once you have your tree of data ready to go, import it into the repository with the svn import command (see the section called “svn import”):

$ svn import /tmp/myproject file:///path/to/repos/myproject -m "initial import"
Adding         /tmp/myproject/branches
Adding         /tmp/myproject/tags
Adding         /tmp/myproject/trunk
Adding         /tmp/myproject/trunk/foo.c
Adding         /tmp/myproject/trunk/bar.c
Adding         /tmp/myproject/trunk/Makefile
…
Committed revision 1.
$ 

Now the repository contains this tree of data. As mentioned earlier, you won't see your files by directly peeking into the repository; they're all stored within a database. But the repository's imaginary filesystem now contains a top-level directory named myproject, which in turn contains your data.

Note that the original /tmp/myproject directory is unchanged; Subversion is unaware of it. (In fact, you can even delete that directory if you wish.) In order to start manipulating repository data, you need to create a new “working copy” of the data, a sort of private workspace. Ask Subversion to “check out” a working copy of the myproject/trunk directory in the repository:

$ svn checkout file:///path/to/repos/myproject/trunk myproject
A  myproject/foo.c
A  myproject/bar.c
A  myproject/Makefile
…
Checked out revision 1.

Now you have a personal copy of part of the repository in a new directory named myproject. You can edit the files in your working copy and then commit those changes back into the repository.

For a full tour of all the things you can do with your working copy, read Chapter 3, Guided Tour.

At this point, you have the option of making your repository available to others over a network. See Chapter 6, Server Configuration to learn about the different sorts of server processes available and how to configure them.