Synchronously open a file and return an instance of Deno.FsFile. The file does not need to previously exist if using the create or createNew open options. The caller may have the resulting file automatically closed by the runtime once it's out of scope by declaring the file variable with the using keyword.

using file = Deno.openSync("/foo/bar.txt", { read: true, write: true });
// Do work with file

Alternatively, the caller may manually close the resource when finished with it.

const file = Deno.openSync("/foo/bar.txt", { read: true, write: true });
// Do work with file
file.close();

Requires allow-read and/or allow-write permissions depending on options.