Return TRUE when R is being used interactively and
FALSE otherwise.
interactive()An interactive R session is one in which it is assumed that there is a human operator to interact with, so for example R can prompt for corrections to incorrect input or ask what to do next or if it is OK to move to the next plot.
GUI consoles will arrange to start R in an interactive session. When
R is run in a terminal (via Rterm.exe on Windows), it
assumes that it is interactive if stdin is connected to a
(pseudo-)terminal and not if stdin is redirected to a file or
pipe. Command-line options --interactive (Unix) and
--ess (Windows, Rterm.exe) override the default
assumption.
(On a Unix-alike, whether the readline command-line editor is
used is not overridden by --interactive.)
Embedded uses of R can set a session to be interactive or not.
Internally, whether a session is interactive determines
how some errors are handled and reported, e.g.see
stop and options("showWarnCalls").
whether one of --save, --no-save or --vanilla is required, and if R ever asks whether to save the workspace.
the choice of default graphics device launched when needed and
by dev.new: see options("device")
whether graphics devices ever ask for confirmation of a new page.
In addition, R's own R code makes use of interactive(): for
example help, debugger and
install.packages do.
# NOT RUN {
.First <- function() if(interactive()) x11()
# }
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