HP-UX Reference (11i v2 04/09) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

intro(7) intro(7)

NAME

intro - introduction to device special ﬁles

DESCRIPTION

This section describes the device special ﬁles used to access

HP peripherals and device drivers. The

names of the entries are generally derived from the type of device being described (disk, terminal, etc.),

not the names of the device special ﬁles or device drivers themselves. Characteristics of both the

hardware device and the corresponding

HP-UX device driver are discussed where applicable.

The devices can be classiﬁed in two categories, raw and block. A raw or character-mode device, such as

a line printer, transfers data in an unbuffered stream and uses a character device special ﬁle.

Block devices, as the name implies, transfer data in blocks by means of the system’s normal buffering

mechanism. Block devices use block device special ﬁles and may have a character device interface too.

A device special ﬁle name becomes associated with a device when the ﬁle is created, using the mksf(1M),

insf(1M), or mknod(1M) commands. When creating device special ﬁles, it is recommended that the fol-

lowing standard naming convention be used:

/dev/preﬁx/devspec[

options]

prefix indicates the subdirectory for the device class (for example,

rdsk for raw device special ﬁles

for disks,

dsk for block device special ﬁles for disks, rmt for raw tape devices).

devspec indicates hardware path information and is typically in the format

c#t#d# as follows:

c# Instance number assigned by the operating system to the interface card. There is

no direct correlation between instance number and physical slot number.

t# Target address on a remote bus (for example, SCSI address).

d# Device unit number at the target address (for example, SCSI LUN).

options Further qualiﬁers, such as disk section

# (for backward compatibility), tape density selection

for a tape device, or surface speciﬁcation for magneto-optical media.

Hardware path information can be derived from ioscan (1M) output.

EXAMPLES

The following is an example of a disk device special ﬁle name:

/dev/dsk/c0t6d0

where dsk indicates block disk access and c0t6d0 indicates disk access at interface card instance 0,

target address 6, and unit 0. Absence of s# indicates access to the entire disk (see disk(7) for details).

The following is an example of a tape device special ﬁle name:

/dev/rmt/c2t3d0QIC150

where rmt indicates raw magnetic tape, c2 indicates that the device is connected to interface card

instance 2, t3 indicates that target device address is set to 3, d0 indicates that the tape transport resides

at unit address 0, and QIC150 identiﬁes the tape format as QIC150 (see mt(7) for details).

WARNINGS

In the past, other naming conventions have been used for device special ﬁles. Using ln(1) to create a link

between the old and new standard name is useful as a temporary expedient until all programs using an

old naming convention have been converted.