+The
+.Ar command
+argument is mandatory unless
+.Fl C ,
+.Fl L ,
+or
+.Fl s
+is specified.
+.Pp
+The user will be required to authenticate by entering their password,
+unless configured otherwise.
+.Pp
+By default, a new environment is created.
+The variables
+.Ev HOME ,
+.Ev LOGNAME ,
+.Ev PATH ,
+.Ev SHELL ,
+and
+.Ev USER
+and the
+.Xr umask 2
+are set to values appropriate for the target user.
+.Ev DOAS_USER
+is set to the name of the user executing
+.Nm .
+The variables
+.Ev DISPLAY
+and
+.Ev TERM
+are inherited from the current environment.
+This behavior may be modified by the config file.
+The working directory is not changed.