setenv[name[value]]
Assign a value to an environment variable name.
By convention, name must be uppercase.
value can be a single word or a quoted string.
If no value is given, the null value is assigned.
With no arguments, display the names and values of all
environment variables. setenv is not necessary for the
USER, TERM, and PATH variables because they are automatically exported
from user, term, and path.
See also "Environment Variables" earlier in this section.