Presenation: Concurrent Versions System (CVS)

Find ppt version (CVSDemo.ppt) in http://groups.yahoo.com/group/bdosdn/files/Seminar20070721/

or read below...


Concurrent Versions System
Presented by:
K. M. Fazle Azim
Member, BDOSDN
fazle_azim@centionsoftware.com

Presented in:
OSS Seminar organized by BDOSDN and IT Bangla Ltd. (Dhaka, Bangladesh, 21 July 2007)


What is a “Versioning System”?
- Record the history of files
- Share code within a group
- Have multiple people edit the same files
- Merge changes from different people
- Go back in time

The Dark Ages
- Saving every version of every file you have ever created.
- Saving current state of project every so often
- This would however waste an enormous amount of disk space.
- People would have to communicate to make sure only one person was editing at a time.

But now CVS in action ...
- CVS allow you to:
 - store and retrieve multiple versions of a file
 - Compare different versions of a file
 - Perform parallel development

- Not just for code:
 - Documentation
 - Config files
 - Etc

Terminology
- Repository
 - Where the source code management system stores its copy of your file

- Sandbox
 - Your personal working copy
 - You make your changes and then put it back in the repository

- Check out / check in
 - You check files out of the repository (into the sandbox)
 - Edit them
 - Check them back into the repository

- Branch
 - Separate development path
 - V1.0 of your program has been released
 - Now you work on v2.0 as a new branch
 - A bug has been found in v1.0 so you make a bug fix and have v1.1

- Merge
 - Eventually, v1.1 has to be merged back into main line of development, into v2.0

DEMO

What we are going to do
- Create a repository
- Put some files into repository
- Check out the files and edit them
 - Insert keyword substitution for documentation
 - Check it back into the repository

cvs command syntax
- Cvs [cvs-options] command [command-options] [command-args]
 - Cvs-options  are for the CVS system itself.
 - The command options and command args are for the subcommand only

Creating a Repository
- Initialize the value of CVSROOT
 - $export CVSROOT=/var/cvs
 - OR
 - $export CVSROOT=:ext:babu@cvs.cention.se:/var/cvs
 - $export  CVS_RSH=ssh

- Run cvs init:
- $cvs init

Putting stuff into the repository to get started
- Have a directory NOT in the repository
- with all your files you want to start with.
- cd into that directory:
- $cd  /home/babu/workDir

CVS Import
- $cvs import project-name vendor-tag release-tag
- Vendor-tag
 - Track 3rd party code, usually not needed
- Release-tag
 - Current revision of vendor branch files

Import example
- cvs import is a good way to bootstrap a bunch of files into a new project
- $cvs import myProject  start sample

Creating a New Sandbox
- cvs checkout project-name
- $cvs checkout myProject
 - Directory myProject  now created in your sandbox and it contains all the files in the myProject directory in the repository

- Now, you can cd to myProject  of sandbox and edit, etc.

Checkin
- The checkin command in CVS is “commit”
- cvs commit [filename1 filename2]
 - Will update repository for the named files
 - If no files named, updates all file changes in the
 - sandbox to the repository

- Note - the repository is not changed until the commit is requested, no matter how much editing you do, so don’t forget to end your session with a commit

To check out a single file
- cvs update [file1 file2 …]
 - Downloads changes from repository to an existing sandbox
 - Merges changes from repository into changed files in the sandbox
 - If no files names, do all files in project

Status and Log
- cvs status [files …]
 - Status of ifles such as current working version and version in the repository

- cvs log [files …]
 - Displays a log regarding files in the current sandbox

Remove a Repository and Release a Sandbox
- cvs remove files
 - Removes files structure from repository

- cvs release [-d] files
 - Releases [-d and removes] the sandbox files