For checkout, rtag, and export, the program is server-based, and as such the following applies:-
If using remote access methods (pserver, ext, etc.), CVS will execute this program on the server from a temporary directory. The path is searched for this program.
If using "local access" (on a local or remote NFS filesystem, i.e. repository set just to a path), the program will be executed from the newly checked-out tree, if found there, or alternatively searched for in the path if not.
The commit and update programs are locally-based, and are run as follows:-
The program is always run locally. One must re-checkout the tree one is using if these options are updated in the modules administrative file. The file CVS/Checkin.prog contains the value of the option `-i' set in the modules file, and similarly for the file CVS/Update.prog and `-u'. The program is always executed from the top level of the checked-out copy on the client. Again, the program is first searched for in the checked-out copy and then using the path.
Note also that the commit and update programs work ONLY when using local repository access -- the files simply aren't created when sources are checked out from a pserver or other remote CVS.
The programs are all run after the operation has effectively completed.