After changes have been made, you need to commit changes to repository.
If filenames are omitted, CVS scans current directory and all subdirectories and commits all modified files in tree.
Example:
$ cvs ci -m "Updated text string to be printed" cvs commit: Examining . Checking in hello.py; /home/cvsroot/hello/hello.py,v <-- hello.py new revision: 1.3; previous revision: 1.2 done $