It currently has the following variables:

• CYGWIN="nodosfilewarning": On Windows, do not warn about MS-DOS style file names.

• R_TESTS="" This variable is set by R CMD check, and makes the child R process load a startup file at startup, from the current working directory, that is assumed to be the /test dirctory of the package being checked. If the current working directory is changed to something else (as it typically is by testthat, then R cannot start. Setting it to the empty string ensures that callr can be used from unit tests.

• R_BROWSER="false": typically we don't want to start up a browser from the child R process.

• R_PDFVIEWER="false": similarly for the PDF viewer.

rcmd_safe_env()

## Value

A named character vector of environment variables.

## Details

Note that callr also sets the R_ENVIRON, R_ENVIRON_USER, R_PROFILE and R_PROFILE_USER environment variables appropriately, unless these are set by the user in the env argument of the r, etc. calls.