110 lines
2.7 KiB
Groff
110 lines
2.7 KiB
Groff
.TH MT 1
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.SH NAME
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mt \- magnetic tape control
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.SH SYNOPSIS
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.B mt
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.RB [ \-f
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.IR device ]
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.RI [ count ]
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.SH DESCRIPTION
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.B Mt
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is a user interface to the magnetic tape commands described in
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.BR mtio (4).
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It allows one to space a tape forwards or backwards, write end of file
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markers, etc.
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.PP
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With the
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.B \-f
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option a tape device can be named, otherwise the environment variable
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.B TAPE
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is used if set. Standard input is used if the tape name is a dash (\-). The
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.I count
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argument is used to tell how many blocks or files to space or how many file
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markers to write. It may be a C-style decimal, octal or hexadecimal constant,
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by default "1".
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.PP
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.I Command
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is the action to perform, it may be one of the following, or any
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unambiguous prefix (like
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.B st
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for
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.BR status ):
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.TP 15
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.B eof, weof
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Write
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.I count
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end-of-file markers.
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.TP
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.B fsf
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Forward space
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.I count
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file markers.
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.TP
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.B fsr
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Forward space
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.I count
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records. (The size of a record depends on the tape, and may even be
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variable, depending on the size of the writes.)
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.TP
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.B bsf
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Backwards space
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.I count
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files. The count may be zero to backspace to the start of the current file.
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(A tape device need not support backwards movement, or may be very slow
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doing it. Rewinding and forward spacing may be better.)
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.TP
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.B bsr
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Backwards space
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.I count
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records. The tape is positioned after the last block of the previous file
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if you hit a filemark when spacing backwards. The block count is set to -1
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to indicate that the driver has no idea where it is on the previous file.
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.TP
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.B eom
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Forward space to the end of media.
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.TP
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.B rewind
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Rewind the tape.
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.TP
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.B offline, rewoffl
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Rewind and take offline. This may cause some drives to eject the tape.
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.TP
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.B status
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Shows the status of the drive, the sense key of the last SCSI error,
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current file number, current record number, residual count if the last
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command that encountered end-of-file, and the current block size.
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.TP
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.B retension
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Removes tape tension by winding and rewinding the tape completely.
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.TP
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.B erase
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Erases the tape completely and rewinds it.
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.TP
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.B density
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Sets the density code to read or write the tape to
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.IR count .
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Density codes supported depend on the drive. This command need not be
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used if the drive senses the proper density on read and can only write
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one density.
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.TP
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.B blksize, blocksize
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Sets the block size used to read or write the tape to
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.IR count .
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This command may be used to select a fixed block size for a variable block
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size tape. This will speed up I/O for small block sizes. Use a zero
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.I count
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to use variable sized blocks again.
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.SH ENVIRONMENT
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.TP 15n
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.B TAPE
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Tape drive to use if set.
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.SH FILES
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.TP 15n
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.B /dev/nrst4
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Default tape device.
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.SH "SEE ALSO"
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.BR mtio (4),
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.BR st (4).
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.SH AUTHOR
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Kees J. Bot (kjb@cs.vu.nl)
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