interactive()
TRUE
if the input to S-PLUS is an interactive
terminal,
FALSE
if it is not.
Use
interactive
to prevent inappropriate
execution.
For example, the
menu
and
browser
functions
only work when executed interactively.
interactive
is
TRUE
if and only if both the standard input
and standard error file descriptors are terminals
(as determined by the isatty system routine).
This is not foolproof.
if(!interactive()) stop("must be interactive")