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.\" Copyright (c) 1981, 1990, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)mt.1 8.1 (Berkeley) 6/6/93
.\"
.Dd June 6, 1993
.Dt MT 1
.Os BSD 4
.Sh NAME
.Nm mt
.Nd magnetic tape manipulating program
.Sh SYNOPSIS
.Nm
.Op Fl f Ar tapename
.Ar command
.Op Ar count
.Sh DESCRIPTION
.Nm Mt
is used to give commands to a magnetic tape drive.
By default
.Nm
performs the requested operation once. Operations
may be performed multiple times by specifying
.Ar count .
Note
that
.Ar tapename
must reference a raw (not block) tape device.
.Pp
The available commands are listed below. Only as many
characters as are required to uniquely identify a command
need be specified.
.Bl -tag -width "eof, weof"
.It Cm weof
Write
.Ar count
end-of-file marks at the current position on the tape.
.It Cm fsf
Forward space
.Ar count
files.
.It Cm fsr
Forward space
.Ar count
records.
.It Cm bsf
Back space
.Ar count
files.
.It Cm bsr
Back space
.Ar count
records.
.It Cm rewind
Rewind the tape
(Count is ignored).
.It Cm offline , rewoffl
Rewind the tape and place the tape unit off-line
(Count is ignored).
.It Cm erase
Erase the tape
(Count is ignored).
.It Cm retension
Re-tension the tape
(one full wind forth and back, Count is ignored).
.It Cm status
Print status information about the tape unit.
.It Cm blocksize
Set the block size for the tape unit. Zero means variable-length
blocks.
.It Cm density
Set the density for the tape unit. For the density codes, see below.
The density value could be given either numerically, or as a string,
corresponding to the
.Dq Reference
field. If the string is abbreviated, it will be resolved in the order
shown in the table, and the first matching entry will be used. If the
given string and the resulting canonical density name do not match
exactly, an informational message is printed about what the given
string has been taken for.
.It Cm eom
Forward space to end of recorded medium
(Count is ignored).
.It Cm eod
Forward space to end of data, identical to
.Cm eom .
.It Cm comp
Set compression mode.
(The kernel counterpart of this has not yet been reported to work
correctly.)
.El
.Pp
If a tape name is not specified, and the environment variable
.Ev TAPE
does not exist;
.Nm
uses the device
.Pa /dev/nrst0 .
.Pp
.Nm Mt
returns a 0 exit status when the operation(s) were successful,
1 if the command was unrecognized, and 2 if an operation failed.
.Pp
The different density codes are as follows:
.Pp
.Dl 0x0 default for device
.Dl 0xE reserved for ECMA
.Bd -literal -offset indent
Value Tracks Density(bpi) Code Type Reference Note
0x1 9 800 NRZI R X3.22-1983 2
0x2 9 1600 PE R X3.39-1986 2
0x3 9 6250 GCR R X3.54-1986 2
0x5 4/9 8000 GCR C X3.136-1986 1
0x6 9 3200 PE R X3.157-1987 2
0x7 4 6400 IMFM C X3.116-1986 1
0x8 4 8000 GCR CS X3.158-1986 1
0x9 18 37871 GCR C X3B5/87-099 2
0xA 22 6667 MFM C X3B5/86-199 1
0xB 4 1600 PE C X3.56-1986 1
0xC 24 12690 GCR C HI-TC1 1,5
0xD 24 25380 GCR C HI-TC2 1,5
0xF 15 10000 GCR C QIC-120 1,5
0x10 18 10000 GCR C QIC-150 1,5
0x11 26 16000 GCR C QIC-320(525?) 1,5
0x12 30 51667 RLL C QIC-1350 1,5
0x13 1 61000 DDS CS X3B5/88-185A 4
0x14 1 43245 RLL CS X3.202-1991 4
0x15 1 45434 RLL CS ECMA TC17 4
0x16 48 10000 MFM C X3.193-1990 1
0x17 48 42500 MFM C X3B5/91-174 1
.Ed
where Code means:
.Bd -literal -offset indent
NRZI Non Return to Zero, change on ones
GCR Group Code Recording
PE Phase Encoded
IMFM Inverted Modified Frequency Modulation
MFM Modified Frequency Modulation
DDS Dat Data Storage
RLL Run Length Encoding
.Ed
where Type means:
.Bd -literal -offset indent
R Reel-to-Reel
C Cartridge
CS cassette
.Ed
where Notes means:
.Bd -literal -offset indent
1 Serial Recorded
2 Parallel Recorded
3 Old format know as QIC-11
4 Helical Scan
5 Not ANSI standard, rather industry standard.
.Ed
.Sh ENVIRONMENT
If the following environment variable exists, it is utilized by
.Nm mt .
.Bl -tag -width Fl
.It Ev TAPE
.Nm Mt
checks the
.Ev TAPE
environment variable if the
argument
.Ar tapename
is not given.
.Sh FILES
.Bl -tag -width /dev/*rst[0-9]*xx -compact
.It Pa /dev/*rwt*
QIC-02/QIC-36 magnetic tape interface
.It Pa /dev/*rst[0-9]*
SCSI magnetic tape interface
.El
.Sh SEE ALSO
.Xr mtio 4 ,
.Xr st 4 ,
.Xr wt 4 ,
.Xr dd 1 ,
.Xr ioctl 2 ,
.Xr environ 7
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
.Pp
Extensions regarding the
.Xr st 4
driver appeared in 386BSD 0.1 as a separate
.Xr st 1
command, and have been merged into the
.Nm
command in
.Fx 2.1 .
.Pp
The former
.Cm eof
command that used to be a synonym for
.Cm weof
has been abandoned in
.Fx 2.1
since it was often confused with
.Cm eom ,
which is fairly dangerous.
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