Detect the current execution context

Identifies which of three execution environments the code is currently running in: an interactive R session, a quarto render call, or a plain Rscript invocation. This is useful for writing code that behaves correctly across all three contexts, such as choosing figure dimensions or deciding whether to report progress.

Usage

detect_execution_context(interactive_fn = interactive)

Arguments

interactive_fn

A function. Used to detect whether the session is interactive. Defaults to base::interactive. Override in tests to simulate different execution environments.

Value

A character string, one of "interactive", "quarto", or "rscript".

Details

To resolve an input data path across the same three contexts, use resolve_input_path(), which calls this function and then validates what the chosen branch produced.

Detection follows a priority order:

1. If interactive() is TRUE, returns "interactive".

2. If the environment variable QUARTO_DOCUMENT_PATH is set and non-empty, returns "quarto".

3. Otherwise, returns "rscript".

The order is unobservable in practice, and that is worth recording so nobody has to re-derive it. QUARTO_DOCUMENT_PATH is set only by Quarto rendering a document, and every path that renders one – quarto render, quarto preview, quarto::quarto_render(), the RStudio Render button – runs the R code in a spawned process that is not interactive. Running chunks inline in RStudio is the reverse case: the session is interactive and the variable is unset (checked in RStudio, September 2026). The two tests therefore never fire together, so there is no case in which the priority arbitrates anything.

See also

resolve_input_path() for the input-path case specifically.

Examples

# \donttest{
# Behave differently depending on where the code is running. Progress
# output is useful at a console and only clutters a cluster job log.
context <- detect_execution_context()

if (context == "rscript") {
  options(cli.progress_show_after = Inf)
}
# }