CVSup is a software package for distributing and updating source trees from a master CVS repository on a remote server host. The FreeBSD sources are maintained in a CVS repository on a central development machine in California. With CVSup, FreeBSD users can easily keep their own source trees up to date.

CVSup uses the so-called pull model of updating. Under the pull model, each client asks the server for updates, if and when they are wanted. The server waits passively for update requests from its clients. Thus all updates are instigated by the client. The server never sends unsolicited updates. Users must either run the CVSup client manually to get an update, or they must set up a cron job to run it automatically on a regular basis.

The term CVSup, capitalized just so, refers to the entire software package. Its main components are the client cvsup which runs on each user's machine, and the server cvsupd which runs at each of the FreeBSD mirror sites.

The easiest way to install CVSup is to use the precompiled net/cvsup package from the FreeBSD packages collection. If you prefer to build CVSup from source, you can use the net/cvsup port instead. But be forewarned: the net/cvsup port depends on the Modula-3 system, which takes a substantial amount of time and disk space to download and build.

CVSup's operation is controlled by a configuration file called the supfile. There are some sample supfiles in the directory /usr/share/examples/cvsup/.

The information in a supfile answers the following questions for CVSup:

In the following sections, we will construct a typical supfile by answering each of these questions in turn. First, we describe the overall structure of a supfile.

A supfile is a text file. Comments begin with # and extend to the end of the line. Lines that are blank and lines that contain only comments are ignored.

Each remaining line describes a set of files that the user wishes to receive. The line begins with the name of a “collection”, a logical grouping of files defined by the server. The name of the collection tells the server which files you want. After the collection name come zero or more fields, separated by white space. These fields answer the questions listed above. There are two types of fields: flag fields and value fields. A flag field consists of a keyword standing alone, e.g., delete or compress. A value field also begins with a keyword, but the keyword is followed without intervening white space by = and a second word. For example, release=cvs is a value field.

A supfile typically specifies more than one collection to receive. One way to structure a supfile is to specify all of the relevant fields explicitly for each collection. However, that tends to make the supfile lines quite long, and it is inconvenient because most fields are the same for all of the collections in a supfile. CVSup provides a defaulting mechanism to avoid these problems. Lines beginning with the special pseudo-collection name *default can be used to set flags and values which will be used as defaults for the subsequent collections in the supfile. A default value can be overridden for an individual collection, by specifying a different value with the collection itself. Defaults can also be changed or augmented in mid-supfile by additional *default lines.

With this background, we will now proceed to construct a supfile for receiving and updating the main source tree of FreeBSD-CURRENT.

You are now ready to try an update. The command line for doing this is quite simple:

where supfile is of course the name of the supfile you have just created. Assuming you are running under X11, cvsup will display a GUI window with some buttons to do the usual things. Press the go button, and watch it run.

Since you are updating your actual /usr/src tree in this example, you will need to run the program as root so that cvsup has the permissions it needs to update your files. Having just created your configuration file, and having never used this program before, that might understandably make you nervous. There is an easy way to do a trial run without touching your precious files. Just create an empty directory somewhere convenient, and name it as an extra argument on the command line:

The directory you specify will be used as the destination directory for all file updates. CVSup will examine your usual files in /usr/src, but it will not modify or delete any of them. Any file updates will instead land in /var/tmp/dest/usr/src. CVSup will also leave its base directory status files untouched when run this way. The new versions of those files will be written into the specified directory. As long as you have read access to /usr/src, you do not even need to be root to perform this kind of trial run.

If you are not running X11 or if you just do not like GUIs, you should add a couple of options to the command line when you run cvsup:

The -g tells CVSup not to use its GUI. This is automatic if you are not running X11, but otherwise you have to specify it.

The -L 2 tells CVSup to print out the details of all the file updates it is doing. There are three levels of verbosity, from -L 0 to -L 2. The default is 0, which means total silence except for error messages.

There are plenty of other options available. For a brief list of them, type cvsup -H. For more detailed descriptions, see the manual page.

Once you are satisfied with the way updates are working, you can arrange for regular runs of CVSup using cron(8). Obviously, you should not let CVSup use its GUI when running it from cron(8).

The file collections available via CVSup are organized hierarchically. There are a few large collections, and they are divided into smaller sub-collections. Receiving a large collection is equivalent to receiving each of its sub-collections. The hierarchical relationships among collections are reflected by the use of indentation in the list below.

The most commonly used collection is src-all.

For the CVSup FAQ and other information about CVSup, see The CVSup Home Page.

Most FreeBSD-related discussion of CVSup takes place on the FreeBSD technical discussions mailing list. New versions of the software are announced there, as well as on the FreeBSD announcements mailing list.

For questions or bug reports about CVSup take a look at the CVSup FAQ.

CVSup servers for FreeBSD are running at the following sites:

Central Servers, Primary Mirror Sites, Armenia, Australia, Brazil, Czech Republic, Denmark, Estonia, Finland, France, Germany, Ireland, Italy, Japan, Korea, Latvia, Lithuania, Netherlands, Norway, Poland, Russia, Slovak Republic, Slovenia, South Africa, Spain, Sweden, Switzerland, Taiwan, Ukraine, USA.

(as of UTC)