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 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
      following 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 s# (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.




 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 intro(7)							    intro(7)




 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.

 SEE ALSO
      ioscan(1M), mksf(1M), insf(1M), lssf(1M), hier(5), introduction(9).

      The system administrator manual for your system.

      Web access to HP-UX documentation at http://docs.hp.com.























 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000