CVS: An Introduction
If you have downloaded software from the Internet, especially from SourceForge, you probably noticed the letters CVS. CVS stands for Concurrent Versions System and is a tool that allows developers to keep track of their projects. It also allows developers to collaborate on projects.
While CVS may be used on large projects with many developers over a network, this article focuses on its usefulness for individuals on local systems. A common occurrence with CVS might begin with making changes to a script or configuration file and then moving on to other tasks. After some time has passed, you find your changes aren't working, and you don't have a backup of the original file, and you can't quite remember all the changes you made. CVS can help prevent this situation because it keeps track of changes made to files and allows you to revert to working versions of them.
Files under the control of CVS are stored in a special directory called a repository, and each file has a revision number maintained by CVS. To make a change to a file, you first must get a copy of it from the repository. You can get a copy of the latest revision of a file or any earlier revision stored in CVS. When you are through working with the file, you put it back into the repository, and its revision number increases incrementally. Each time you commit a file to the repository you can supply a log message that helps keep track of which changes were made to the file over time.
CVS differs from other version control systems in that it doesn't lock files; different developers can check out a file and work on it at the same time. CVS makes sure one developer's edits don't conflict with edits made by another developer when the file is put back into the repository. If conflicts are found, CVS places markers in the second developer's copy of the file, allowing him or her to find and resolve the conflicts. Once the conflicts are resolved, the developer then commits the file to the repository.
There is nothing tricky involved in installing CVS. You can either download and compile the source or install an RPM package or its equivalent.
Once CVS is installed you will have to decide where to locate the repository. It should be in a partition that has a good amount of free space and one to which you have write permission. Once you have decided on a location for the repository, you have to create it and populate it with CVS administration files. This is done using the CVS init command. If you want your repository to be in /usr/local/cvsstuff, you would execute the CVS command shown below:
cvs -d /usr/local/cvsstuff init
The CVSROOT environment variable, or -d switch, tells CVS commands which repository to act upon. The CVSROOT variable can be set by adding the following line to your .bash_profile:
To put existing projects into the repository, use the import command. For example, say you have the directory structure shown below and will add other client directories in the future.
html_projects/ client1/ images/ client2/ images/
To place html_projects and everything under it into the repository, you would use the following commands:
cd html_projects cvs import -m "Put html_projects in the repository" html_projects vendor releaseThe -m option supplies a log message for the transaction; if you don't use it CVS starts your default editor so you can type a message, then finishes the operation when you exit the editor. The vendor and release tags aren't used by CVS but are required nonetheless. A typical vendor tag could be your company name, and “start” makes a good release tag. If your project contains binary files, such as pictures, read up on the -k option to ensure they are copied into the repository correctly.
If you were to now look in your repository, you should find a directory called html_projects containing copies of all the files in the original html_projects directory.
Creating a new project under CVS is simply a matter of creating an empty directory structure and then importing it into the repository via the import command. As you create the files for the new project, use the CVS add command to put them in the repository.
|Using Salt Stack and Vagrant for Drupal Development||May 20, 2013|
|Making Linux and Android Get Along (It's Not as Hard as It Sounds)||May 16, 2013|
|Drupal Is a Framework: Why Everyone Needs to Understand This||May 15, 2013|
|Home, My Backup Data Center||May 13, 2013|
|Non-Linux FOSS: Seashore||May 10, 2013|
|Trying to Tame the Tablet||May 08, 2013|
- Making Linux and Android Get Along (It's Not as Hard as It Sounds)
- RSS Feeds
- New Products
- Using Salt Stack and Vagrant for Drupal Development
- Drupal Is a Framework: Why Everyone Needs to Understand This
- A Topic for Discussion - Open Source Feature-Richness?
- Home, My Backup Data Center
- Validate an E-Mail Address with PHP, the Right Way
- New Products
- Tech Tip: Really Simple HTTP Server with Python
- Ahh, the Koolaid.
4 hours 44 min ago
- git-annex assistant
10 hours 44 min ago
- direct cable connection
11 hours 6 min ago
- Agreed on AirDroid. With my
11 hours 17 min ago
- I just learned this
11 hours 21 min ago
11 hours 51 min ago
- not living upto the mobile revolution
14 hours 42 min ago
- Deceptive Advertising and
15 hours 18 min ago
- Let\'s declare that you have
15 hours 19 min ago
- Alterations in Contest Due
15 hours 20 min ago
Enter to Win an Adafruit Prototyping Pi Plate Kit for Raspberry Pi
It's Raspberry Pi month at Linux Journal. Each week in May, Adafruit will be giving away a Pi-related prize to a lucky, randomly drawn LJ reader. Winners will be announced weekly.
Fill out the fields below to enter to win this week's prize-- a Prototyping Pi Plate Kit for Raspberry Pi.
Congratulations to our winners so far:
- 5-8-13, Pi Starter Pack: Jack Davis
- 5-15-13, Pi Model B 512MB RAM: Patrick Dunn
- Next winner announced on 5-21-13!
Free Webinar: Linux Backup and Recovery
Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.
In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.