What is CVS?

CVS is a version control system. It is used to record the history of your source files.

Bugs can creep in when software is modified, and may not be detected until a long time after the modification is made. With CVS, you can retrieve old versions to find which change caused the bug.

CVS can also help when a project is being worked on by multiple people, where overwriting each others changes is easy to do. CVS solves this problem by having each developer work in his/her own directory and then instructing CVS to merge the work when each developer is done.

CVS Documents https://www.cvshome.org/docs/

CVS Manual https://www.cvshome.org/docs/manual/

Online Introduction to CVS: https://www.cvshome.org/docs/blandy.html

Revision and Branch

                                                     +-------------+

                           Branch 1.2.2.3.2 ->        ! 1.2.2.3.2.1 !

                                                    / +-------------+

                 +---------+    +---------+    +---------+

Branch 1.2.2 -> _! 1.2.2.1 !----! 1.2.2.2 !----! 1.2.2.3 !

               / +---------+    +---------+    +---------+

+-----+    +-----+    +-----+    +-----+    +-----+

! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !  <- The main trunk

+-----+    +-----+    +-----+    +-----+    +-----+

                !   +---------+    +---------+    +---------+

Branch 1.2.4 -> +---! 1.2.4.1 !----! 1.2.4.2 !----! 1.2.4.3 !

                    +---------+    +---------+    +---------+

Use CVS for class project

Set up the repository

Each group has its own repository: /classes/cs3141/project/group#/src

Set up CVSROOT

csh

$setenv CVSROOT /classes/cs3141/project/group#/src

bsh

$CVSROOT=/classes/cs3141/project/group#/src

$export CVSROOT

run cvs init

$cvs init

‘cvs init’ creates a dir named CVSROOT under $CVSROOT. Do not remove the diretory CVSROOT

Import code to CVS repository

If you want to put some existing project files under CVS control, you can use the import function.

To import a project, run the command below,

$cvs import –m “log msg” projnam vendortag releasetag

-m: the first log file for the entire project

projnam : the directory name that will be created in CVS repository

Example:

$cd myproj

$cvs import –m “initial import into CVS” myproj jrandom start

Every file (include files under subdirs) will be checked into repository. Cleanup files under myproj first!

If you just want to create a new project, first create a empty directory and then perform the above import.

Example:

$mkdir myproj

$cd myproj

$cvs import –m “initial import into CVS” myproj jrandom start

Checking out project source codes to a working directory

$cd {desired_working_directory}

$cvs checkout {projectname}

A directory named {desired_working_directory}/{projectname} will be created, all the latest version of source code will be extracted and put under the dir.

$cd {projectname}

Making changes to files

$vi

$make

Compile your code … Debug it … Test it …

Committing your changes

$cvs update

$cvs commit {filename}

You can specify the filename to commit only one file, instead of all files for that project.

Merging your changes

$ cvs update

Verify and test the merged files with other people’s change.

Examining changes

$cvs log {filename}

This command shows all the comments associated with each commit command.

$cvs diff –c –r 1.6 –r 1.7 {filename}

This command shows all the content change between two versions.

Adding and deleting files

create the new file

$cvs add {filename}

$cvs commit {filename}

delete the file

$cvs rm {filename}

$cvs commit {filename}

Writing good log entries

Why the change was made? Not just what was the change.

Handling conflicts

More than one people made change in some spot.

Very rare.

check the status of a file

$cvs status {filename}

Up-to-date

The file is identical with the latest revision in the repository.

Locally Modified

You have edited the file, and not yet committed your changes.

Needing Patch

Someone else has committed a newer revision to the repository.

Needs Merge

Someone else has committed a newer revision to the repository, and you have also made modifications to the file.

Access control: who can checkout/checkin the file?

The permission can be controlled by file permission settings in the repository.

Use eclipse in CVS

Initialize the repository and import your files as in step 1 and step 2.

Open a new project with CVS wizard, or open project, then click Window -> Open Perspective-> CVS repository exploring

Add a new repository using

Host: wopr.csl.mtu.edu or Joshua.csl.mtu.edu

Repository path: the full path of the directory where repository was created. ( basically the value of CVSROOT env as in step1)

Authentication: the lab account and password

Connection: extssh

https://www.cvshome.org/docs/manual/

Using keyword expansion

keywords:

$Author$

$Date$

$ID$

$Revision$

$Source$

$Log$

Example:

The header of server.java was:

// $Source$

// $Date$

// $Revision$

// $Id$

// $Author$

// $Log$

after importing into CVS and being checked out, the keywords were replaced with values

// $Source: /home/csdept/ruihong/CVSROOT/poker/server.java,v $

// $Date: 2005/01/27 03:08:00 $

// $Revision: 1.1.1.1 $

// $Id: server.java,v 1.1.1.1 2005/01/27 03:08:00 ruihong Exp $

// $Author: ruihong $

// $Log: server.java,v $

// Revision 1.1.1.1 2005/01/27 03:08:00 ruihong

// initial import into CVS

After making some change and a commit,

[ruihong@icu20 ~/poker]$ more server.java

// $Source: /home/csdept/ruihong/CVSROOT/poker/server.java,v $

// $Date: 2005/01/27 03:12:04 $

// $Revision: 1.2 $

// $Id: server.java,v 1.2 2005/01/27 03:12:04 ruihong Exp $

// $Author: ruihong $

// $Log: server.java,v $

// Revision 1.2 2005/01/27 03:12:04 ruihong

// This is just a test to see header change.

// Revision 1.1.1.1 2005/01/27 03:08:00 ruihong

// initial import into CVS

This is a test for checking new logs appended in the header

Exercise

The goal of this exercise is to get familiar with CVS.

1. Create a new directory under your home directory and check your existing
project source code into the new repository.

2. Checkout the project from CVS into a new working directory.

3. (Optional) delete the original directory

4. Under working directory, modify some files. Commit the change.

5. Add some keywords in the header of the files. Commit the change.

6. Create a new file say README in the working dir, check it into CVS.

7. Simulate the situation that multiple developer working on the same source code.
           Checkout the project from CVS to a second working directory.
             Change a file in the first dir and commit it .
             Change the same file in the second dir and commit it.
             Do you see the merge of both changes after you commit it? Try to make it work.

8. run "cvs log"

9. tagging ( tag files for releases)

10. branching ( make a new branch out of the trunk for maintenance)