You may not need to set CVSROOT if your cvs binary has the right path compiled in; use 'cvs -v' to display all compiledin paths.
CVSREAD If this is set, checkout and update will try hard to make the files in your working directory readonly. When this is not set, the default behavior is to permit modification of your working files.
RCSBIN Specifies the full pathname where to find RCS programs,such as co(1) and ci(1). If not set, a compiledinvalue is used; see the display from 'cvs -v'.
EDITOR Specifies the program to use for recording log messages during commit. If not set, the default is /usr/ucb/vi.