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Read a Line of Input from the User in Both Interactive and Non-Interactive Sessions

Source: R/RcppExports.R
getline.Rd

Provides a safe and portable way to prompt the user for input from the terminal, working seamlessly in both interactive R sessions and non-interactive Rscript sessions (when connected to a TTY).

Usage

getline(prompt)

Arguments

prompt

A character string to display as the input prompt.

Value

A character string with the user's input, or NULL (R_NilValue) if input is cancelled via Escape (ESC, ASCII 27) or EOF (Ctrl+D or equivalent).

Details

In an interactive session (e.g., RStudio or R console), this function delegates to base R's readline(). In non-interactive contexts where a TTY is available, it switches the terminal to non-canonical mode and performs low-level character-by-character input handling with support for echoing, backspace editing, and cancellation via Escape or EOF. Ctrl+C will terminate the process as usual.

  • Supports visible typing and live editing with backspace.

  • Returns early with NULL if the user presses Escape or EOF.

  • Uses raw terminal input in non-interactive mode; requires that stdin is a TTY.

  • Does not intercept Ctrl+C; this will terminate the process as normal.

Examples

if (FALSE) { # \dontrun{
  # In Rscript or R console
  input <- readline_safe("Enter your name: ")
  if (!is.null(input)) cat("Hello,", input, "!\n")
} # }