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71c04358ef
designed to work with rdump(8) to remote disk. -d <directory> confines rmt to operate within a single directory. -r enforces read-only mode. -w enforces write-only mode. This is quite usable with public ssh key setup, e.g. having the following in .ssh/authorized/keys: command="/etc/rmt -rd /backups/machine.example.conf",no-agent-forwarding,... ssh-rsa AAAAB3... ok semarie@
220 lines
5.6 KiB
Groff
220 lines
5.6 KiB
Groff
.\" $OpenBSD: rmt.8,v 1.13 2015/09/20 10:05:48 halex Exp $
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.\"
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.\" Copyright (c) 1983, 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)rmt.8 6.5 (Berkeley) 3/16/91
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.\"
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.Dd $Mdocdate: September 20 2015 $
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.Dt RMT 8
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.Os
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.Sh NAME
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.Nm rmt
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.Nd remote magtape protocol module
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.Sh SYNOPSIS
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.Nm
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.Op Fl r | w
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.Op Fl d Ar directory
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.Sh DESCRIPTION
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.Nm
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is a program used by the remote dump and restore programs
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through an interprocess communication connection.
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Traditionally it is used for manipulating a magnetic tape drive but it may
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be used for regular file access as well.
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.Nm
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is normally started up with an
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.Xr rcmd 3
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or
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.Xr rcmdsh 3
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call.
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl d Ar directory
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Confine file access to
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.Ar directory .
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Forward slashes in filenames are disallowed and symlinks are not followed.
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.It Fl r
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Read-only mode, suitable for use with
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.Xr rrestore 8 .
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.It Fl w
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File write mode, suitable for use with
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.Xr rdump 8
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for dumping to regular files.
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Creates missing files and refuses to open existing ones.
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The file permission bits are set to readonly.
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.El
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.Pp
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The
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.Nm
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program accepts requests specific to the manipulation of
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magnetic tapes, performs the commands, then responds with
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a status indication.
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All responses are in ASCII and in one of two forms.
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Successful commands have responses of:
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.Pp
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.D1 Sy A Ns Ar number Ns \en
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.Pp
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.Ar number
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is an ASCII representation of a decimal number.
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Unsuccessful commands are responded to with:
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.Bd -filled -offset indent
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.Sm off
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.Sy E Ar error-number No \en Ar error-message No \en
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.Sm on
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.Ed
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.Pp
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.Ar error-number
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is one of the possible error
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numbers described in
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.Xr intro 2
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and
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.Ar error-message
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is the corresponding error string as printed
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from a call to
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.Xr perror 3 .
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The protocol is comprised of the
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following commands, which are sent as indicated - no spaces are supplied
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between the command and its arguments, or between its arguments, and
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.Ql \en
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indicates that a newline should be supplied:
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.Bl -tag -width Ds
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.Sm off
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.It Xo Ic \&O Ar device
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.No \en Ar mode No \en
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.Xc
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.Sm on
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Open the specified
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.Ar device
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using the indicated
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.Ar mode .
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.Ar device
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is a full pathname and
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.Ar mode
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is an ASCII representation of a decimal
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number suitable for passing to
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.Xr open 2 .
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If a device had already been opened, it is
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closed before a new open is performed.
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.It Ic C Ns Ar device Ns \en
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Close the currently open device.
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The
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.Ar device
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specified is ignored.
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.Sm off
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.It Xo Ic L
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.Ar offset No \en
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.Ar whence No \en
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.Xc
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.Sm on
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Perform an
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.Xr lseek 2
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operation using the specified parameters.
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The response value is that returned from the
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.Xr lseek 2
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call.
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.It Ic W Ns Ar count Ns \en
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Write data onto the open device.
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.Nm
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reads
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.Ar count
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bytes from the connection, aborting if
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a premature end-of-file is encountered.
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The response value is that returned from
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the
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.Xr write 2
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call.
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.It Ic R Ns Ar count Ns \en
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Read
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.Ar count
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bytes of data from the open device.
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If
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.Ar count
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exceeds the size of the data buffer (10 kilobytes), it is
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truncated to the data buffer size.
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.Nm
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then performs the requested
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.Xr read 2
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and responds with
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.Sy A Ns Ar count-read Ns \en
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if the read was
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successful; otherwise an error in the
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standard format is returned.
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If the read was successful, the data read is then sent.
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.Sm off
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.It Xo Ic I Ar operation
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.No \en Ar count No \en
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.Xc
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.Sm on
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Perform an
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.Dv MTIOCOP
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.Xr ioctl 2
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command using the specified parameters.
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The parameters are interpreted as the
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ASCII representations of the decimal values
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to place in the
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.Ar mt_op
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and
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.Ar mt_count
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fields of the structure used in the
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.Xr ioctl 2
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call.
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The return value is the
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.Ar count
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parameter when the operation is successful.
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.It Ic S
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Return the status of the open device, as
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obtained with a
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.Dv MTIOCGET
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.Xr ioctl 2
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call.
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If the operation was successful, an
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.Dq ack
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is sent with the size of the status buffer, then the status buffer is
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sent (in binary).
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.El
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.Pp
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Any other command causes
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.Nm
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to exit.
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.Sh DIAGNOSTICS
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All responses are of the form described above.
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.Sh SEE ALSO
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.Xr rcmd 3 ,
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.Xr rcmdsh 3 ,
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.Xr mtio 4 ,
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.Xr rdump 8 ,
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.Xr rrestore 8
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.Bx 4.2 .
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.Sh BUGS
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People tempted to use this for a remote file access protocol
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are discouraged.
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