cvs Command in Linux

cvs (Concurrent Version System) is a command used in Linux for version control that allows you to manage changes to files and directories over time. With the help of cvs command, you can track your project’s history, revert to the previous version and merge changes from different contributors. This command is pretty useful in software development, where maintaining a clear and organized history of code changes is crucial.

By using cvs command on Linux, you can work more efficiently and ensure working with the most up-to-date project’s version.

Here is a comprehensive guide to the options available with the cvs command −

Installation of cvs Command
Syntax of cvs Command
cvs Command Options
Examples of cvs Command in Linux

Installation of cvs Command

By default, cvs command is not installed on Linux systems, however, you can manually install it from your default Linux package manager.

On Linux systems like Ubuntu, Debian and other such systems that use APT package manager, you can install cvs utility from the following command −

sudo apt install cvs

If you are using distributions that do not use APT as the default package manager (such as Fedora, CentOS, and Arch Linux), utilize the appropriate package managers to install CVS on these systems.

On Fedora, you can install cvs from the following command −

sudo dnf install cvs

For CentOS, the cvs utility can be installed by using −

sudo yum install cvs

If you are Arch Linux users, simply execute the below-given command −

sudo pacman -S cvs

Once, you installed the cvs utility, confirm the version by using the below-given command −

cvs --version

Syntax of cvs Command

The basic syntax for the cvs command in Linux is as follows −

cvs [options] command [arguments]

Here, options represent any additional flags or settings you want to apply, command is the specific CVS operation (For example, checkout, commit, update). While arguments are the relevant file or directory names.

cvs Command Options

Let’s explore different options that can be used with the cvs command −

Option	Description
-allow-root=rootdir	Specify the repository on the command line and define the legal CVS root directory.
-d cvs_root_directory	Use cvs_root_directory as the path name for the repository, overriding $CVSROOT.
-e editor-command	Specify the editor command for entering log information, overriding $CVSEDITOR and $EDITOR.
-f	Forces the operation (e.g., force a checkout even if files are locally modified).
-H, --help	Show helpful information about the available options and their usage.
-l	Locks files (prevents others from modifying them).
-n	Perform a dry run and simulate the operation without making changes to the root repository. It also prints out the actions that would occur if the -n flag were not used.
-Q	Quiet mode, and is less verbose than normal.
-q	Suppress normal output (quiet mode).
-r revision	Specify a specific revision to work with (e.g., -r 1.5).
-R	Recurse into subdirectories (e.g., for add, commit, and update).
-u	Updates files to the latest revision on the branch.
-v	Show cvs version and exit.
-w	Make new working files read-write; overrides the setting of the $CVSREAD environment variable.

Essential CVS Commands in Linux

The cvs also offers a wide range of commands to efficiently manage file history; here are some of the key commands −

Option	Description
add	Introduce a new file or directory to the repository.
admin	Manage administrative tasks for RCS.
annotate	Display the last revision where each line was changed.
checkout	Save changes to the repository.
commit	Compare differences between file revisions.
diff	Show differences between revisions.
edit	Prepare to edit a watched file.
editors	See who is editing a watched file.
export	Export sources from CVS in a manner similar to performing a checkout
history	Display the access history of the repository.
import	Bring external sources into CVS by utilizing vendor branches.
init	Set up a new CVS repository if it doesn’t exist.
log	Show historical data for files.
rdiff	Generate ‘patch’ format differences between revisions.
status	Show the status of checked-out files.
unedit	Revert an edit command.
update	Synchronize your working directory with the repository.
version	Display the current CVS version(s).
watch	Set up watches on files.

Examples of cvs Command in Linux

Before you work with the cvs command, you must set up your environment on your Linux system. For that purpose, open your .bashrc file and add the lines given below for setting the environment variables.

export CVSROOT='/home/ubuntu/cvs_root'
export CVSEDITOR=/bin/nano

The first line is the Directory for CVS source code repository while the second line specifies your preferred text editor.

Once done, save the file and reload your shell or run −

source ~/.bashrc

For csh users, they can add the following lines inside the .csh file −

setenv CVSROOT '/home/ubuntu/cvs_root'  
setenv CVSEDITOR /bin/nano

Now, let’s move towards practical examples of cvs commands in Linux.

Creating a Repository
Adding a Project
Checking Out a Project
Adding Sub-directories or Files
Committing the File
Update the Working Directory
Remove Files from CVS

Creating a Repository

To create a repository with cvs, you must specify the directory where it will be stored. For example, if your repository directory is /home/ubuntu/cvs_root, you can initialize it with the following command −

cvs -d /home/ubuntu/cvs_root init

The above command will set up the cvs repository and allow you to version control your files.

Adding a Project

Once you created the repository, you can add a project by using the import command with cvs. For example, to add a project let’s say “testfile” with the description “CVS START”, simply use the below-given command −

cvs import -m "CVS START" cvs_file test_file start

The above command will import the “myfile” project into the CVS repository and then associate it with the “cvs_file” module.

Checking Out a Project

If you want to work on a project, you must check it out from the repository, creating a local copy. You can use the checkout command with the file or project name, which is cvs_file in our case, as given below −

cvs checkout cvs_file

The command provided above will retrieve the project files from the repository and after that, create a local working copy on your machine. Thus allows you to make changes and track revisions.

Adding Sub-directories or Files

You can also add sub-directories or new files to your project by using the add keyword with the cvs command. For example, for adding a new file like cvs_file_1 to your project, simply run the below-given command −

cvs add cvs_file_1

Committing the File

After you have made changes to your project files, simply commit them to the repository to permanently save the changes. For that purpose, commit command is used like this:

cvs commit myfile

The above command will update the repository with the current newest version of myfile and record the changes you made on the system.

Update the Working Directory

You can update the working directory of cvs project with the help of command provided below −

cvs update

The command provided above will synchronize your working directory with the latest versions of files in the repository.

Remove Files from CVS

Apart from that, you can also remove files from your project by using the cvs remove command followed by the file name using the below-given command −

cvs remove file_name

The above command will permanently delete your desired file from the cvs repository, and ensure it is no longer tracked.

Conclusion

The cvs command is used in Linux for file version control. In this guide, we have discussed the syntax of cvs command, its different available options and demonstrated them with the help of examples. After following these examples, you will be able to effectively manage your cvs projects, track revisions as well as synchronize them with the repository.

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