GDAL's virtual file systems — vfs

Every GDAL path works here, not only files on disk. /vsimem/ is memory, /vsizip/ and /vsitar/ look inside archives, /vsicurl/ and the cloud prefixes reach remote storage, and they compose: /vsizip//vsicurl/https://example.org/a.zip/b.tif is a file inside a zip that is never downloaded whole.

Usage

vfs_list(path, limit = -1L)

vfs_stat(path)

vfs_exists(path)

Arguments

path: A VSI path.
limit: Roughly the most entries to list. -1, the default, is all of them; a limit is what makes listing a large remote prefix bearable. GDAL reads a directory in chunks and stops at the first chunk past the limit, so a listing can come back a little longer than asked for.

Value

vfs_list() a character vector of names, or NULL. vfs_stat() a list of size, is_directory and modified, or NULL. vfs_exists() TRUE or FALSE.

Details

vfs_list() returns NULL rather than an error for a path that is not a directory or holds nothing, since a caller cannot otherwise tell the two apart. vfs_stat() returns NULL for a path that is not there.

Examples

vfs_exists(system.file("extdata/test.tif", package = "GDAL7"))
#> [1] TRUE
vfs_stat(system.file("extdata/test.tif", package = "GDAL7"))$size
#> [1] 428

# What ships with the package.
vfs_list(system.file("extdata", package = "GDAL7"))
#> [1] "."                    "strings.zarr"         "temperature.icechunk"
#> [4] "test.tif"             "multidim.zarr"        "strings.nc"          
#> [7] "overviews.tif"        "test.gpkg"            ".."