Is R Running Interactively?

Description

Return TRUE when R is being used interactively and FALSE otherwise.

Usage

interactive()

Details

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.

Note

This is a primitive function.

See Also

source, .First

Examples

 .First <- function() if(interactive()) x11()