A.3 匿名 CVS

A.3.1 簡介

Anonymous CVS (or, as it is otherwise known, anoncvs) is a feature provided by the CVS utilities bundled with FreeBSD for synchronizing with a remote CVS repository. Among other things, it allows users of FreeBSD to perform, with no special privileges, read-only CVS operations against one of the FreeBSD project's official anoncvs servers. To use it, one simply sets the CVSROOT environment variable to point at the appropriate anoncvs server, provides the well-known password “anoncvs” with the cvs login command, and then uses the cvs(1) command to access it like any local repository.

Note: The cvs login command, stores the passwords that are used for authenticating to the CVS server in a file called .cvspass in your HOME directory. If this file does not exist, you might get an error when trying to use cvs login for the first time. Just make an empty .cvspass file, and retry to login.

While it can also be said that the CVSup and anoncvs services both perform essentially the same function, there are various trade-offs which can influence the user's choice of synchronization methods. In a nutshell, CVSup is much more efficient in its usage of network resources and is by far the most technically sophisticated of the two, but at a price. To use CVSup, a special client must first be installed and configured before any bits can be grabbed, and then only in the fairly large chunks which CVSup calls collections.

Anoncvs, by contrast, can be used to examine anything from an individual file to a specific program (like ls or grep) by referencing the CVS module name. Of course, anoncvs is also only good for read-only operations on the CVS repository, so if it is your intention to support local development in one repository shared with the FreeBSD project bits then CVSup is really your only option.

A.3.2 使用匿名 CVS

Configuring cvs(1) to use an Anonymous CVS repository is a simple matter of setting the CVSROOT environment variable to point to one of the FreeBSD project's anoncvs servers. At the time of this writing, the following servers are available:

Since CVS allows one to “check out” virtually any version of the FreeBSD sources that ever existed (or, in some cases, will exist), you need to be familiar with the revision (-r) flag to cvs(1) and what some of the permissible values for it in the FreeBSD Project repository are.

There are two kinds of tags, revision tags and branch tags. A revision tag refers to a specific revision. Its meaning stays the same from day to day. A branch tag, on the other hand, refers to the latest revision on a given line of development, at any given time. Because a branch tag does not refer to a specific revision, it may mean something different tomorrow than it means today.

Section A.7 contains revision tags that users might be interested in. Again, none of these are valid for the Ports Collection since the Ports Collection does not have multiple revisions.

When you specify a branch tag, you normally receive the latest versions of the files on that line of development. If you wish to receive some past version, you can do so by specifying a date with the -D date flag. See the cvs(1) manual page for more details.

A.3.3 範例

While it really is recommended that you read the manual page for cvs(1) thoroughly before doing anything, here are some quick examples which essentially show how to use Anonymous CVS:

Example A-1. Checking Out Something from -CURRENT (ls(1)):

% setenv CVSROOT :pserver:anoncvs@anoncvs.tw.FreeBSD.org:/home/ncvs
% cvs login
At the prompt, enter any word for “password”.
% cvs co ls

Example A-2. Using SSH to check out the src/ tree:

% cvs -d freebsdanoncvs@anoncvs.FreeBSD.org:/home/ncvs co src
The authenticity of host 'anoncvs.freebsd.org (' can't be established.
DSA key fingerprint is 52:02:38:1a:2f:a8:71:d3:f5:83:93:8d:aa:00:6f:65.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'anoncvs.freebsd.org' (DSA) to the list of known hosts.

Example A-3. Checking Out the Version of ls(1) in the 6-STABLE Branch:

% setenv CVSROOT :pserver:anoncvs@anoncvs.tw.FreeBSD.org:/home/ncvs
% cvs login
At the prompt, enter any word for “password”.
% cvs co -rRELENG_6 ls

Example A-4. Creating a List of Changes (as Unified Diffs) to ls(1)

% setenv CVSROOT :pserver:anoncvs@anoncvs.tw.FreeBSD.org:/home/ncvs
% cvs login
At the prompt, enter any word for “password”.
% cvs rdiff -u -rRELENG_5_3_0_RELEASE -rRELENG_5_4_0_RELEASE ls

Example A-5. Finding Out What Other Module Names Can Be Used:

% setenv CVSROOT :pserver:anoncvs@anoncvs.tw.FreeBSD.org:/home/ncvs
% cvs login
At the prompt, enter any word for “password”.
% cvs co modules
% more modules/modules

A.3.4 其他資源

The following additional resources may be helpful in learning CVS:


若有 FreeBSD 方面疑問,請先閱讀 FreeBSD 相關文件,如不能解決的話,再洽詢 <questions@FreeBSD.org>。
關於本文件的問題,請洽詢 <doc@FreeBSD.org>。