Figure 3: Some important device special files and permissions

File       Description                    Mode   Owner   Group
/dev/mem   Entire system memory           0640   root    kmem
/dev/kmem  Kernel memory                  0640   root    kmem
/dev/rwd*  Byte-level disk access         0640   root    operator
/dev/wd*   Block-level disk access        0640   root    operator
/dev/rsd*  Byte-level SCSI disk access    0640   root    operator
/dev/sd*   Block-level SCSI disk access   0640   root    operator