GDAL's configuration options — gdal

GDAL reads these at the moment it needs them, so setting one changes how the next call behaves. They steer caching, credentials, and a good deal of per-driver behaviour: GDAL_CACHEMAX is the block cache size, CPL_VSIL_CURL_ALLOWED_EXTENSIONS limits what /vsicurl/ will fetch, AWS_NO_SIGN_REQUEST makes an S3 bucket public.

Usage

gdal_config(name, value)

gdal_config_options()

with_gdal_config(options, expr)

Arguments

name: The option's name.
value: Its value, or NULL to unset it. A logical is written as GDAL writes them, "YES" or "NO".
options: A named character vector or list of options to set.
expr: The expression to evaluate with them set.

Value

gdal_config() reading returns a string or NULL, and setting returns the previous value invisibly. gdal_config_options() returns every option that is set, as a named character vector. with_gdal_config() returns what expr returned.

Details

gdal_config() with a value sets one; with only a name it reads one, and returns NULL when it is not set, which is not the same as being set to the empty string. with_gdal_config() sets options for one expression and puts back exactly what was there, including unsetting what was unset.

Examples

# Read a raster with GDAL's block cache set small, then leave it as it was.
with_gdal_config(c(GDAL_CACHEMAX = "16"), {
  gdal_config("GDAL_CACHEMAX")
})
#> [1] "16"

gdal_config("GDAL_CACHEMAX")
#> NULL