Concurrent Versions System, a revision control system. More information: https://cvs.nongnu.org.
CVSROOT
environment variable to be set externally):cvs -d path/to/repository init
cvs import -m "message" project_name version vendor
cvs checkout project_name
cvs diff path/to/file
cvs add path/to/file
cvs commit -m "message" path/to/file
cvs update