CVS ??

1
CVS ??

• ????????
• ???
• ltchihchun_at_digitalsesame.comgt
• 2001/8/18

2
??

• CVS ??
• CVS ??
• CVS ?? (Linux/Windows)
• CVS ????
• CVS ???????

3
CVS ??

• What is CVS ?
• Idea of CVS
• Benefits, Fancy features

4
What Is Concurrent Versions System ?

• Version controll system
• Multi-developer environment

5
Version Management

• Software Development
• Website Management
• Documentations
• Synchronization of distributed effort
• ... anywhere digital data evolves

6
Requirements for VC

• Multiple Developers - concurrent Access
• History
• View diffs
• Rollback changes
• Release Management

7
Idea of CVS

• The idea of the CVS is to create a filesystem,
  where each file has remembers all the
  modifications made to it. In other words it is
  all the versions of it at the same time.
• Filesystem resides in a repository, that can be
  stored to local or remote host.
• All the files are edited outside of the
  repository in some working directory and in some
  phase synchronized with the repository.
• Files are moved to, from and updated from
  repository with special tool called cvs, which is
  available for most platforms

8
So What is it good for ?

• Version controll and connecting multiple
  developer together in one project, of course )
• Document management and archiving
• Nice way to do one project with multiple machines
  and still manage the versions
• Allows free experimenting on project
• Following the growth of the project
• Backupping - it forces one to take backups with
  neglible work very often

9
Benefits of CVS

• Automatic, constant and forced backupping
• When programming, frees the development
• Gives freedom to choose afterwards, when the
  program is ready
• Saves all the versions for later use
• Clean way of saving only the necessary files and
  managing projects
• Gives freedom to develop on multiple machines
  simultaneously

10
Fancy Features

• Multiple developer support (file locking, etc.)
• Bonsai - www-interface (for example see Gnome
  project)
• Keyword substitutions
• Development of several version at the same time
• Multiplatform-support (works even on obscure
  platforms like Windows)

11
Essential CVS Terminology - Repository

• CVS stores all files in a centralized directory
  called the repostiory. The directory is defined
  by the environment variable CVSROOT.

12
Essential CVS Terminology - Module

• Modules are just the toplevel directories in the
  Repository.
• You can combine multiple modules in your own
  directory structure. See documentation for
  CVSROOT/modules
• incorporate generic libraries in your own
  sourcetree, but be able to maintain them
  individually.
• The files in the repository are organized in
  modules. Each module is made up of one or more
  files, and can include files from several
  directories. A typical usage is to define one
  module per project.

13
Version Numbers

• Every file in a CVS repository can contain many
  versions, which are given version numbers in form
  x.y.x.y....
• The history of each file is tracked with an
  incrementing revision number
• For each revision there is a log entry
• Revision numbers have the format 1.25 if they're
  on the main trunk, branches have something like
  1.33.2.16

14
Version Numbers

• Version numbering is automatic i.e. number y is
  automatically incresed avary time file is
  changed

1.1
1.2
1.3
1.4
1.5
15
Release Management

• marking important stages in the development e.g.
  milestones, code freezes or actual releases
• We want to reproduce the same state later.
• making bug-fix releases, starting at a specific
  release.
• newly added files should not show up in the old
  release
• files which are deleted in the meantime should
  still show up if we reproduce the old state.

16
Tags

• A Tag is simply a symbolic name for a specific
  revision
• Tagging all files in one directory or module
  marks the current stage.
• Can be used as synonym for a revision in any
  CVS-command
• cvs tag lttagnamegt applies the tag to the current
  revision of each file
• Version numbers can be treated as a internal
  information in CVS and only symbolic names - tags
  for version used to mark releases.

17
Branches

• Version number can contain more than two numbers
  to mark branches.
• Branch can start from any version and start
  depeloping independently from the rest of the
  software.
• In some point of the development of a branch, it
  can be merged to main trunk in necessary.

18
Interaction with the repository

• Check out
• Syntax cvs checkout options module ...
• Add
• Syntax cvs add options file ...
• Remove
• Syntax cvs remove options file ...
• Examine status
• Syntax cvs status options file ...

19
Interaction with the repository count.

• Update
• Syntax cvs update options file ...
• Check in (commit)
• Syntax cvs commit options file ...
• Release module
• Syntax cvs release options module ...
• Import module
• Syntax cvs import options repository_dir
  vendor_tag release_tag
• Export module
• Syntax cvs export options module ...

20
Conflict Resolution

• Conflicts are rare, since most concurrent editing
  is done at different places in the file
• usually easy to resolve - if not, there seems to
  be a communication problem in the group in
  general
• On conflict, both parts are shown in the file, to
  be resolved by hand. See demo.

21
References

• CVS-Site
• lthttp//www.cvshome.org/gt
• WinCVS Windows Client
• lthttp//www.wincvs.org/gt

22
QA

• Your time.