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Read a single keypress at the terminal

Source: R/keypress.R
keypress.Rd

It currently only works at Linux/Unix and OSX terminals, and at the Windows command line. see has_keypress_support.

Usage

keypress(block = TRUE, timeout = Inf)

Arguments

block

Whether to wait for a key press, if there is none available now.

timeout

Maximum number of seconds to wait for a key press, if block is TRUE. The default Inf waits indefinitely. If no key is pressed before the timeout expires, NA is returned. Ignored for non-blocking reads (block = FALSE). The wait is interruptible regardless of the timeout.

Value

The key pressed, a character scalar. NA is returned if no key is available: for non-blocking reads, or when a blocking read times out.

Details

The following special keys are supported:

  • Arrow keys: 'up', 'down', 'right', 'left'.

  • Function keys: from 'f1' to 'f12'.

  • Others: 'home', 'end', 'insert', 'delete', 'pageup', 'pagedown', 'tab', 'enter', 'backspace' (same as 'delete' on OSX keyboards), 'escape'.

  • Control with one of the following keys: 'a', 'b', 'c', 'd', 'e', 'f', 'h', 'k', 'l', 'n', 'p', 't', 'u', 'w'.

See also

Other keypress function: has_keypress_support()

Examples

if (FALSE) {
x <- keypress()
cat("You pressed key", x, "\n")

# Wait at most five seconds for a key press
x <- keypress(timeout = 5)
if (is.na(x)) cat("No key pressed\n") else cat("You pressed key", x, "\n")
}