device_maps File

Device maps are created when you set up device allocation for your system. The /etc/security/device_maps file includes the device names, device types, and device-special files that are associated with each allocatable device.

The device_maps file defines the device-special file mappings for each device, which in many cases is not intuitive. This file allows programs to discover which device-special files map to which devices. You can use the dminfo command, for example, to retrieve the device name, the device type, and the device-special files to specify when you set up an allocatable device. The dminfo command uses the device_maps file to report this information.

Each device is represented by a one-line entry in the following format:

device-name:device-type:device-list

Example 4-10 Sample device_maps Entry

The following example shows an entry in a device_maps file.

audio0:\
audio:\
/dev/audio /dev/audioctl /dev/dsp /dev/dsp0 /dev/mixer0 /dev/sound/0 
/dev/sound/0ctl /dev/sound/audio810\:0mixer /dev/sound/audio810\:0dsp 
/dev/sound/audio810\:0 /dev/sound/audio810\:0ctl

Lines in the device_maps file can end with a backslash (\) to continue an entry on the next line. Comments can also be included. A pound sign (#) comments all subsequent text until the next newline that is not immediately preceded by a backslash. Leading and trailing blanks are allowed in any field. The fields are defined as follows:

device-name

Specifies the name of the device. For a list of current device names, see Viewing Allocation Information About a Device.

device-type

Specifies the generic device type. The generic name is the name for the class of devices, such as st, fd, rmdisk, or audio. The device-type field logically groups related devices.

device-list

Lists the device-special files that are associated with the physical device. The device-list must contain all of the special files that allow access to a particular device. If the list is incomplete, a malevolent user can still obtain or modify private information. Valid entries for the device-list field reflect the device files that are located in the /dev directory.