| 1 | .TH MTIO 4
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| 2 | .SH NAME
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| 3 | mtio \- magnetic tape commands
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| 4 | .SH SYNOPSIS
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| 5 | .B "#include <sys/types.h>"
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| 6 | .br
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| 7 | .B "#include <sys/mtio.h>"
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| 8 | .br
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| 9 | .B "#include <sys/ioctl.h>"
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| 10 | .SH DESCRIPTION
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| 11 | .de SP
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| 12 | .if t .sp 0.4
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| 13 | .if n .sp
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| 14 | ..
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| 15 | The magnetic tape devices described in
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| 16 | .BR sd (4)
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| 17 | may be sent commands or queried for their status using the following ioctl
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| 18 | calls:
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| 19 | .PP
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| 20 | .RS
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| 21 | .BR ioctl ( \fIfd ,
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| 22 | .BR MTIOCTOP ,
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| 23 | .RB & "struct mtop" )
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| 24 | .br
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| 25 | .BR ioctl ( \fIfd ,
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| 26 | .BR MTIOCGET ,
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| 27 | .RB & "struct mtget" )
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| 28 | .RE
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| 29 | .PP
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| 30 | The struct mtop, struct mtget and associated definitions are defined in
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| 31 | <sys/mtio.h> as follows:
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| 32 | .PP
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| 33 | .nf
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| 34 |
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| 35 | /* Tape operations: ioctl(fd, MTIOCTOP, &struct mtop) */
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| 36 |
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| 37 | .ta +4n +7n +15n
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| 38 | struct mtop {
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| 39 | short mt_op; /* Operation (MTWEOF, etc.) */
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| 40 | int mt_count; /* Repeat count. */
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| 41 | };
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| 42 |
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| 43 | .ta +17n +5n
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| 44 | #define MTWEOF 0 /* Write End-Of-File Marker */
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| 45 | #define MTFSF 1 /* Forward Space File mark */
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| 46 | #define MTBSF 2 /* Backward Space File mark */
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| 47 | #define MTFSR 3 /* Forward Space Record */
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| 48 | #define MTBSR 4 /* Backward Space Record */
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| 49 | #define MTREW 5 /* Rewind tape */
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| 50 | #define MTOFFL 6 /* Rewind and take Offline */
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| 51 | #define MTNOP 7 /* No-Operation, set status only */
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| 52 | #define MTRETEN 8 /* Retension (completely wind and rewind) */
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| 53 | #define MTERASE 9 /* Erase the tape and rewind */
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| 54 | #define MTEOM 10 /* Position at End-Of-Media */
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| 55 | #define MTMODE 11 /* Select tape density */
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| 56 | #define MTBLKZ 12 /* Select tape block size */
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| 57 |
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| 58 | /* Tape status: ioctl(fd, MTIOCGET, &struct mtget) */
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| 59 |
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| 60 | .ta +4n +7n +15n
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| 61 | struct mtget {
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| 62 | short mt_type; /* Type of tape device. */
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| 63 |
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| 64 | /* Device dependent "registers". */
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| 65 | short mt_dsreg; /* Drive status register. */
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| 66 | short mt_erreg; /* Error register. */
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| 67 |
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| 68 | /* Misc info. */
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| 69 | off_t mt_resid; /* Residual count. */
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| 70 | off_t mt_fileno; /* Current File Number. */
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| 71 | off_t mt_blkno; /* Current Block Number within file. */
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| 72 | off_t mt_blksize; /* Current block size. */
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| 73 | };
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| 74 |
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| 75 | .fi
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| 76 | .PP
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| 77 | See
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| 78 | .BR mt (1)
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| 79 | for a detailed description on what each operation does. The mt_type field
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| 80 | is always zero, there is no use for it yet. Mt_dsreg is 0 (OK), 1 (Error),
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| 81 | or 2 (EOF encountered.) Mt_erreg holds the SCSI sense key of the last
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| 82 | operation. Mt_blksize is the current tape block size in bytes, zero if the
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| 83 | block size is variable.
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| 84 | .PP
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| 85 | Note that one can issue these commands on a file descriptor that is in use
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| 86 | to read or write data, something that
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| 87 | .B mt
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| 88 | can't do. So you can add eof markers in the middle of an output stream,
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| 89 | or get the status of a device before a rewind-on-close tape rewinds.
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| 90 | .PP
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| 91 | The driver will automatically add an end of file marker to a tape that is
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| 92 | written to if you execute a space command. If you write eof markers
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| 93 | yourself then the driver will not add one extra on close.
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| 94 | .SH "SEE ALSO"
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| 95 | .BR mt (1),
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| 96 | .BR sd (4).
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| 97 | .SH AUTHOR
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| 98 | Kees J. Bot (kjb@cs.vu.nl)
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