CVSup is a software package for transferring and updating collections of files across a network. It consists of a server called cvsupd and a client called cvsup. CVSup is faster and more flexible than traditional network packages such as rdist and sup. In addition, CVSup has special knowledge of RCS files .

Application. A application that will upgrade to date the ports tree and/ or the source files for FreeBSD. Works with ports-supfile, stable-supfile standard-supfile. To work this command you basically do this: cvsup /"directory location"/"location of supfile" Read more here.Man pages here

CVSup® is a computer program which synchronises files and directories from one location to another while minimizing data transfer using file-type specific delta encoding when appropriate. CVSup was designed for keeping source code repositories - such as CVS - synchronised, but has been extended to support synchronising any type of file.