mtio(4) [minix man page]

MTIO(4) 						     Kernel Interfaces Manual							   MTIO(4)

NAME

       mtio - magnetic tape commands

SYNOPSIS

       #include <sys/types.h>
       #include <sys/mtio.h>
       #include <sys/ioctl.h>

DESCRIPTION

       The magnetic tape devices described in sd(4) may be sent commands or queried for their status using the following ioctl calls:

	      ioctl(fd, MTIOCTOP, &struct mtop)
	      ioctl(fd, MTIOCGET, &struct mtget)

       The struct mtop, struct mtget and associated definitions are defined in <sys/mtio.h> as follows:

       /* Tape operations: ioctl(fd, MTIOCTOP, &struct mtop) */

       struct mtop {
	   short  mt_op;	 /* Operation (MTWEOF, etc.) */
	   int	  mt_count;	 /* Repeat count. */
       };

       #define MTWEOF	0    /* Write End-Of-File Marker */
       #define MTFSF	1    /* Forward Space File mark */
       #define MTBSF	2    /* Backward Space File mark */
       #define MTFSR	3    /* Forward Space Record */
       #define MTBSR	4    /* Backward Space Record */
       #define MTREW	5    /* Rewind tape */
       #define MTOFFL	6    /* Rewind and take Offline */
       #define MTNOP	7    /* No-Operation, set status only */
       #define MTRETEN	8    /* Retension (completely wind and rewind) */
       #define MTERASE	9    /* Erase the tape and rewind */
       #define MTEOM	10   /* Position at End-Of-Media */
       #define MTMODE	11   /* Select tape density */
       #define MTBLKZ	12   /* Select tape block size */

       /* Tape status: ioctl(fd, MTIOCGET, &struct mtget) */

       struct mtget {
	   short  mt_type;	 /* Type of tape device. */

	   /* Device dependent "registers". */
	   short  mt_dsreg;	 /* Drive status register. */
	   short  mt_erreg;	 /* Error register. */

	   /* Misc info. */
	   off_t  mt_resid;	 /* Residual count. */
	   off_t  mt_fileno;	 /* Current File Number. */
	   off_t  mt_blkno;	 /* Current Block Number within file. */
	   off_t  mt_blksize;	 /* Current block size. */
       };

       See  mt(1) for a detailed description on what each operation does.  The mt_type field is always zero, there is no use for it yet.  Mt_dsreg
       is 0 (OK), 1 (Error), or 2 (EOF encountered.)  Mt_erreg holds the SCSI sense key of the last operation.	Mt_blksize  is	the  current  tape
       block size in bytes, zero if the block size is variable.

       Note  that  one can issue these commands on a file descriptor that is in use to read or write data, something that mt can't do.	So you can
       add eof markers in the middle of an output stream, or get the status of a device before a rewind-on-close tape rewinds.

       The driver will automatically add an end of file marker to a tape that is written to if you execute a space  command.   If  you	write  eof
       markers yourself then the driver will not add one extra on close.

SEE ALSO

       mt(1), sd(4).

AUTHOR

       Kees J. Bot (kjb@cs.vu.nl)

																	   MTIO(4)

MT(1)							      General Commands Manual							     MT(1)

NAME

       mt - magnetic tape control

SYNOPSIS

       mt [-f device] [count]

DESCRIPTION

       Mt  is a user interface to the magnetic tape commands described in mtio(4).  It allows one to space a tape forwards or backwards, write end
       of file markers, etc.

       With the -f option a tape device can be named, otherwise the environment variable TAPE  is  used  if  set,  otherwise  the  default  device
       /dev/nrst4 is assumed.  Standard input is used if the tape name is a dash (-).  The count argument is used to tell how many blocks or files
       to space or how many file markers to write.  It may be a C-style decimal, octal or hexadecimal constant, by default "1".

       Command is the action to perform, it may be one of the following, or any unambiguous prefix (like st for status):

       eof, weof      Write count end-of-file markers.

       fsf	      Forward space count file markers.

       fsr	      Forward space count records.  (The size of a record depends on the tape, and may even be variable, depending on the size	of
		      the writes.)

       bsf	      Backwards  space count files.  The count may be zero to backspace to the start of the current file.  (A tape device need not
		      support backwards movement, or may be very slow doing it.  Rewinding and forward spacing may be better.)

       bsr	      Backwards space count records.  The tape is positioned after the last block of the previous file if you hit a filemark  when
		      spacing backwards.  The block count is set to -1 to indicate that the driver has no idea where it is on the previous file.

       eom	      Forward space to the end of media.

       rewind	      Rewind the tape.

       offline, rewoffl
		      Rewind and take offline.	This may cause some drives to eject the tape.

       status	      Shows  the  status  of the drive, the sense key of the last SCSI error, current file number, current record number, residual
		      count if the last command that encountered end-of-file, and the current block size.

       retension      Removes tape tension by winding and rewinding the tape completely.

       erase	      Erases the tape completely and rewinds it.

       density	      Sets the density code to read or write the tape to count.  Density codes supported depend on the drive.  This  command  need
		      not be used if the drive senses the proper density on read and can only write one density.

       blksize, blocksize
		      Sets  the  block	size used to read or write the tape to count.  This command may be used to select a fixed block size for a
		      variable block size tape.  This will speed up I/O for small block sizes.	Use a zero count  to  use  variable  sized  blocks
		      again.

ENVIRONMENT

       TAPE	      Tape drive to use if set.

FILES

       /dev/nrst4     Default tape device.

SEE ALSO

       mtio(4), st(4).

AUTHOR

       Kees J. Bot (kjb@cs.vu.nl)

																	     MT(1)