Whether to build vignettes for package trees.
This is only used if the package is obtained from a package tree,
and not from a source (or binary) package archive. By default
vignettes are not built in this case. If you set this to \code{TRUE},
then you need to make sure that the vignette builder packages are
available, as these are not installed by default currently.

Directory to download the packages to. Defaults to a temporary
directory within the R session temporary directory, see
\code{\link[base:tempfile]{base::tempdir()}}.

CRAN mirror to use. Defaults to the \code{repos} option
(see \code{\link[base:options]{base::options()}}), if that's not set then
\verb{https://cran.rstudio.com}. See also \code{\link[pak:repo_add]{pak::repo_add()}} and
\code{\link[pak:repo_get]{pak::repo_get()}}

Whether or not to update submodules in git repositories. This
affects \verb{git::} and \verb{gitlab::} package sources only.
If the R package is in a subdirectory then only the submodules
within that directory are updated. If a submodule appears in
\code{.Rbuildignore}, then it is skipped.

Whether to always include \code{LinkingTo} dependencies in the solution
of and installation, even if they are needed because the packages
are installed from binaries. This is sometimes useful, see e.g.
\url{https://github.com/r-lib/pak/issues/485} for an example use case.

Package library to install packages to. It is also used for
already installed packages when considering dependencies.

Location of metadata replica of
\code{\link[pkgcache:cranlike_metadata_cache]{pkgcache::cranlike_metadata_cache}}. Defaults to a temporary
directory within the R session temporary directory, see
\code{\link[base:tempfile]{base::tempdir()}}.

A time interval as a \link{difftime} object. pak will update the
metadata cache if it is older than this. The default is one day.
The \code{PKG_METADATA_UPDATE_AFTER} environment variable may be set
in seconds (\code{s} suffix), minutes (\code{m} suffix), hours (\code{h} suffix),
or days (\code{d} suffix). E.g: \verb{1d} means one day.