NAME

intro − introduction to special files

DESCRIPTION

This section describes various special files that refer to specific HP peripherals and device drivers.  The names of the entries are generally derived from the type of device being described (disk, plotter, etc.), not the names of the special files themselves.  Characteristics of both the hardware device and the corresponding HP-UX device driver are discussed where applicable. 

The devices are divided into two categories, unblocked and blocked.  An unblocked device is also called a raw or a character-mode device.  An unblocked device such as a line printer uses a character special file. 

Blocked devices, as the name implies, transfer data in blocks by means of the system’s normal buffering mechanism.  Block devices use block special files. 

For specific details about the default special files shipped with your system, consult the system administrator manuals for your system. 

A name becomes associated with a specific device when the special file is created for that device by using the mkdev(1M) script or mknod(1M) command. When creating special files, it is recommended that the following naming convention be followed. For disk and tape, it is identical with that used on other UNIX systems, and is independent of the hardware. 

The following format is for 9 track tape device file names:

/dev/{r}mt/(c#d)#[hml]{c}{n}

where r indicates a raw device, c#d indicates the controller number (which is optionally specified by the system administrator), # is the device number, hml indicates the density (h (high) for 6250 bpi, m (medium) for 1600 bpi, and l (low) for 800 bpi), c indicates data compression, and n indicates no rewind on close, e.g., /dev/mt/2mn. 

The following format is for hard disk device file names:

/dev/{r}dsk/(r)(c#d)#s#

where r indicates a raw interface to the disk, the second r indicates that this disk is on a remote system, the c#d indicates the controller number (which is optionally specified by the system administrator), and #s# indicates the drive and section numbers, respectively. 

WARNINGS

Several other naming conventions have been used in the past for given devices.  Using ln(1) to create a link between the old name and the new standard name is useful as a temporary expedient until all programs using the old naming convention have been converted.

In general, device drivers are not portable across systems.  However, every effort has been made to make their behavior portable.  Due to variation in hardware, this is not always possible.  Programs that use these drivers directly are at higher-than-average risk of not being portable. 

SEE ALSO

hier(5). 

The introduction to this manual. 

The system administrator manual for your system. 

Hewlett-Packard Company  —  HP-UX Release 8.05: June 1991