DESCRIPTION
getrawpartition() returns the partition number ( ‘a' == 0, ‘b' == 1, ...) of the “raw” partition of the system's disks, or -1 in case of an error, setting the global
errno variable. The possible values for
errno are the same as in
sysctl(3). The “raw” partition is defined as the partition which provides access to the entire disk, regardless of the disk's partition map.