220 lines
5.4 KiB
Groff
220 lines
5.4 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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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.\" @(#)rmt.8 8.3 (Berkeley) 6/1/94
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.\" $FreeBSD$
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.\"
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.Dd June 1, 1994
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.Dt RMT 8
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.Os BSD 4.2
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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 rmt
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.Sh DESCRIPTION
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.Nm Rmt
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is a program used by the remote dump and restore programs
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in manipulating a magnetic tape drive through an interprocess
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communication connection.
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.Nm Rmt
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is normally started up with an
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.Xr rexec 3
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or
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.Xr rcmd 3
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call.
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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. All responses are in
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.Tn ASCII
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and in
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one of two forms.
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Successful commands have responses of:
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.Bd -filled -offset indent
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.Sm off
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.Sy A Ar number No \en
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.Sm on
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.Ed
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.Pp
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.Ar Number
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is an
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.Tn ASCII
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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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.Xo Sy E Ar error-number
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.No \en Ar error-message
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.No \en
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.Xc
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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 Sy \&O Ar device
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.No \en Ar mode No \en
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.Xc
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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
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.Tn ASCII
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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 Xo Sy C Ar device No \en
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.Xc
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Close the currently open device. The
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.Ar device
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specified is ignored.
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.It Xo Sy L
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.Ar whence No \en
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.Ar offset 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
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call.
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.Sm off
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.It Sy W Ar count No \en
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.Sm on
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Write data onto the open device.
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.Nm Rmt
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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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.Sm off
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.It Sy R Ar count No \en
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.Sm on
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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 Rmt
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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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.Sm off
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.Sy A Ar count-read No \en
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.Sm on
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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. If the read
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was successful, the data read is then sent.
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.Sm off
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.It Xo Sy 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 a
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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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.Tn ASCII
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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
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call. 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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.ne 1i
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.It Sy 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
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call. If the operation was successful,
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an ``ack'' is sent with the size of the
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status buffer, then the status buffer is
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sent (in binary).
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.El
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.Sm on
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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 rexec 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 BUGS
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People should be discouraged from using this for a remote
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file access protocol.
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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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