.Rbuildignore has a regular expression on each line, but it's usually easier to work with specific file names. By default, use_build_ignore() will (crudely) turn a filename into a regular expression that will only match that path. Repeated entries will be silently removed.

use_build_ignore() is designed to ignore individual files. If you want to ignore all files with a given extension, consider providing an "as-is" regular expression, using escape = FALSE; see examples.

use_build_ignore(files, escape = TRUE)

}