Wait for a Key Press in a Terminal

Wait for a single key press at the 'R' prompt. This works in terminals, but does not currently work in the 'Windows' 'GUI', the 'OS X' 'GUI' ('R.app'), in 'Emacs' 'ESS', in an 'Emacs' shell buffer or in 'R Studio'. In these cases 'keypress' stops with an error message.

Installation

devtools::install_github("gaborcsardi/keypress")

Usage

> has_keypress_support()
[1] TRUE

> x <- keypress()
> cat("You pressed key", x, "\n")
You pressed key h

Support

This is unfortunately impossible to do in

• RStudio,
• R.app (the builtin OSX GUI),
• RGui (the builtin Windows GUI),
• Emacs ESS, or
• if stdin() is not a terminal.

In other words, it pretty much only works interactively, in a terminal. The terminal can be pretty much any Linux, OSX, or other Unix terminal or Windows cmd (also called RTerm in R).

Keys

Note that not all keys are supported, in particular the modifiers (ctrl, alt, etc.) are not. Supported special keys are:

• Arrow keys: up, down, right, left. Available on most keyboards.
• Function keys: from f1 to f12. Available on most keyboards.
• Others: home, end, insert, delete, pageup, pagedown. Note that these are not available on OSX keyboards, so it is not a good idea to use them.

License

MIT © Gábor Csárdi