[dump.git] / rmt / rmt.8.in

.\" Copyright (c) 1983, 1991, 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. 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.
.\"
.\"     $Id: rmt.8.in,v 1.10 2003/03/30 15:40:40 stelian Exp $
.\"
.TH RMT 8 "version __VERSION__ of __DATE__" BSD "System management commands"
.SH NAME
rmt \- remote magtape protocol module
.SH SYNOPSIS
.B rmt
.SH DESCRIPTION
.B Rmt
is a program used by the remote 
.BR dump (8),
.BR restore (8)
or
.BR tar (1)
programs in manipulating a magnetic tape drive through an interprocess
communication connection.
.B Rmt
is normally started up with an
.BR rexec (3)
or
.BR rcmd (3)
call.
.PP
The 
.B rmt
program accepts requests specific to the manipulation of magnetic tapes, 
performs the commands, then responds with a status indication.  All responses 
are in
.B ASCII
and in one of the following two forms.
.PP
Successful commands have responses of:
.RS
.B A\fInumber\fR\en
.RE
.PP
where
.I number
is an
.B ASCII
representation of a decimal number.
.PP
Unsuccessful commands are responded to with:
.RS
.B E\fIerror-number\fR\en\fIerror-message\fR\en
.RE
.PP
where 
.I error-number
is one of the possible error numbers described in
.BR intro (2)
and
.I error-message
is the corresponding error string as printed from a call to
.BR perror (3).
.PP
The protocol is comprised of the following commands, which are sent as 
indicated - no spaces are supplied between the command and its arguments, or
between its arguments, and \en indicates that a newline should be supplied:
.TP
.B O\fIdevice\fR\en\fImode\fR\en
Open the specified 
.I device
using the indicated
.IR mode .
.I Device
is a full pathname and
.I mode
is an
.B ASCII
representation of a decimal number suitable for passing to
.BR open (2).
If a device had already been opened, it is closed before a new open is
performed.
.TP
.B C\fIdevice\fR\en
Close the currently open device.  The
.I device
specified is ignored.
.TP
.B L\fIwhence\fR\en\fIoffset\fR\en
Perform an
.BR lseek (2)
operation using the specified parameters. The response value is that returned
from the
.B lseek
call.
.TP
.B W\fIcount\fR\en
Write data onto the open device.
.B Rmt
reads
.I count
bytes from the connection, aborting if a premature end-of-file is encountered.
The response value is that returned from the
.BR write (2)
call.
.TP
.B R\fIcount\fR\en
Read
.I count
bytes of data from the open device. If
.I count
exceeds the size of the data buffer (10 kilobytes), it is truncated to the 
data buffer size.
.B Rmt
then performs the requested 
.BR read (2)
and responds with 
.B A\fIcount-read\fR\en
if the read was successful; otherwise an error in the standard format is 
returned. If the read was successful, the data read is then sent.
.TP
.B I\fIoperation\fR\en\fIcount\fR\en
Perform a
.B MTIOCOP
.BR ioctl (2)
command using the specified parameters.  The parameters are interpreted as the
.B ASCII
representations of the decimal values to place in the 
.B mt_op
and
.B mt_count
fields of the structure used in the
.B ioctl
call.  The return value is the
.I count
parameter when the operation is successful.
.IP
By issuing the
.B I-1\en0\en
command, a client will specify that he is using the VERSION 1 protocol.
.IP
For a VERSION 0 client, the
.I operation
parameter is the platform 
.B mt_op
value (could be different if the client and the
.B rmt
server are on two different platforms). For a VERSION 1 client, the 
.I operation
parameter is standardized as below:
.RS
.TP
.B 0
Issue a 
.B MTWEOF
command (write
.I count
end-of-file records).
.TP
.B 1
Issue a 
.B MTFSF
command (forward space over
.I count
file marks).
.TP
.B 2
Issue a 
.B MTBSF
command (backward space over
.I count
file marks).
.TP
.B 3
Issue a 
.B MTFSR 
command (forward space
.I count
inter-record gaps).
.TP
.B 4
Issue a 
.B MTBSR
command (backward space
.I count
inter-record gaps).
.TP
.B 5
Issue a 
.B MTREW
command (rewind).
.TP
.B 6
Issue a 
.B MTOFFL
command (rewind and put the drive offline).
.TP
.B 7
Issue a
.B MTNOP
command (no operation, set status only).
.RE
.TP
.B i\fIoperation\fR\en\fIcount\fR\en
Perform an extended
.B MTIOCOP
.BR ioctl (2)
command using the specified parameters. The parameters are interpreted as the
.B ASCII
representations of the decimal values to place in the 
.B mt_op
and
.B mt_count
fields of the structure used in the
.B ioctl
call.  The return value is the
.I count
parameter when the operation is successful. The possible operations are:
.RS
.TP
.B 0
Issue a 
.B MTCACHE
command (switch cache on).
.TP
.B 1
Issue a 
.B MTNOCACHE
command (switch cache off).
.TP
.B 2
Issue a 
.B MTRETEN
command (retension the tape).
.TP
.B 3
Issue a 
.B MTERASE
command (erase the entire tape).
.TP
.B 4
Issue a 
.B MTEOM
command (position to end of media).
.TP
.B 5
Issue a 
.B MTNBSF
command (backward space count files to BOF).
.RE
.TP
.B S
Return the status of the open device, as obtained with a
.B MTIOCGET
.B ioctl
call.  If the operation was successful, an \*(lqack\*(rq is sent with the size
of the status buffer, then the status buffer is sent (in binary, which is
non-portable between different platforms).
.TP
.BI s sub-command
This is a replacement for the previous 
.B S 
command, portable across different platforms. If the open device is a magnetic
tape, return members of the magnetic tape status structure, as obtained with a
.B MTIOCGET 
ioctl call. If the open device is not a magnetic tape, an error is returned. If
the 
.B MTIOCGET
operation was successful, the numerical value of the structure member is 
returned in decimal. The following sub commands are supported:
.RS
.TP
.B T
return the content of the structure member
.B mt_type
which contains the type of the magnetic tape device.
.TP
.B D
return the content of the structure member
.B mt_dsreg
which contains the "drive status register".
.TP
.B E
return the content of the structure member
.B mt_erreg
which contains the "error register". This structure member must be retrieved
first because it is cleared after each
.B MTIOCGET
ioctl call.
.TP
.B R
return the content of the structure member
.B mt_resid
which contains the residual count of the last I/O.
.TP
.B F
return the content of the structure member
.B mt_fileno
which contains the file number of the current tape position.
.TP
.B B
return the content of the structure member
.B mt_blkno
which contains the block number of the current tape position.
.TP
.B f
return the content of the structure member
.B mt_flags
which contains MTF_ flags from the driver.
.TP
.B b
return the content of the structure member
.B mt_bf
which contains the optimum blocking factor.
.RE
.PP
Any other command causes 
.B rmt
to exit.
.SH DIAGNOSTICS
All responses are of the form described above.
.SH SEE ALSO
.BR rcmd (3),
.BR rexec (3),
.I /usr/include/sys/mtio.h,
.BR rdump (8),
.BR rrestore (8)
.SH BUGS
People should be discouraged from using this for a remote file access protocol.
.SH AUTHOR
The
.B dump/restore
backup suit was ported to Linux's Second Extended File System by Remy Card
<card@Linux.EU.Org>. He maintained the initial versions of 
.B dump
(up and including 0.4b4, released in january 1997).
.PP
Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
.SH AVAILABILITY
The
.B dump/restore
backup suit is available from <http://dump.sourceforge.net>
.SH HISTORY
The
.B rmt
command appeared in 4.2BSD.
Commit	Line	Data
	1	.\" Copyright (c) 1983, 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. Neither the name of the University nor the names of its contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
	28	.\" $Id: rmt.8.in,v 1.10 2003/03/30 15:40:40 stelian Exp $
	29	.\"
	30	.TH RMT 8 "version __VERSION__ of __DATE__" BSD "System management commands"
	31	.SH NAME
	32	rmt \- remote magtape protocol module
	33	.SH SYNOPSIS
	34	.B rmt
	35	.SH DESCRIPTION
	36	.B Rmt
	37	is a program used by the remote
	38	.BR dump (8),
	39	.BR restore (8)
	40	or
	41	.BR tar (1)
	42	programs in manipulating a magnetic tape drive through an interprocess
	43	communication connection.
	44	.B Rmt
	45	is normally started up with an
	46	.BR rexec (3)
	47	or
	48	.BR rcmd (3)
	49	call.
	50	.PP
	51	The
	52	.B rmt
	53	program accepts requests specific to the manipulation of magnetic tapes,
	54	performs the commands, then responds with a status indication. All responses
	55	are in
	56	.B ASCII
	57	and in one of the following two forms.
	58	.PP
	59	Successful commands have responses of:
	60	.RS
	61	.B A\fInumber\fR\en
	62	.RE
	63	.PP
	64	where
	65	.I number
	66	is an
	67	.B ASCII
	68	representation of a decimal number.
	69	.PP
	70	Unsuccessful commands are responded to with:
	71	.RS
	72	.B E\fIerror-number\fR\en\fIerror-message\fR\en
	73	.RE
	74	.PP
	75	where
	76	.I error-number
	77	is one of the possible error numbers described in
	78	.BR intro (2)
	79	and
	80	.I error-message
	81	is the corresponding error string as printed from a call to
	82	.BR perror (3).
	83	.PP
	84	The protocol is comprised of the following commands, which are sent as
	85	indicated - no spaces are supplied between the command and its arguments, or
	86	between its arguments, and \en indicates that a newline should be supplied:
	87	.TP
	88	.B O\fIdevice\fR\en\fImode\fR\en
	89	Open the specified
	90	.I device
	91	using the indicated
	92	.IR mode .
	93	.I Device
	94	is a full pathname and
	95	.I mode
	96	is an
	97	.B ASCII
	98	representation of a decimal number suitable for passing to
	99	.BR open (2).
	100	If a device had already been opened, it is closed before a new open is
	101	performed.
	102	.TP
	103	.B C\fIdevice\fR\en
	104	Close the currently open device. The
	105	.I device
	106	specified is ignored.
	107	.TP
	108	.B L\fIwhence\fR\en\fIoffset\fR\en
	109	Perform an
	110	.BR lseek (2)
	111	operation using the specified parameters. The response value is that returned
	112	from the
	113	.B lseek
	114	call.
	115	.TP
	116	.B W\fIcount\fR\en
	117	Write data onto the open device.
	118	.B Rmt
	119	reads
	120	.I count
	121	bytes from the connection, aborting if a premature end-of-file is encountered.
	122	The response value is that returned from the
	123	.BR write (2)
	124	call.
	125	.TP
	126	.B R\fIcount\fR\en
	127	Read
	128	.I count
	129	bytes of data from the open device. If
	130	.I count
	131	exceeds the size of the data buffer (10 kilobytes), it is truncated to the
	132	data buffer size.
	133	.B Rmt
	134	then performs the requested
	135	.BR read (2)
	136	and responds with
	137	.B A\fIcount-read\fR\en
	138	if the read was successful; otherwise an error in the standard format is
	139	returned. If the read was successful, the data read is then sent.
	140	.TP
	141	.B I\fIoperation\fR\en\fIcount\fR\en
	142	Perform a
	143	.B MTIOCOP
	144	.BR ioctl (2)
	145	command using the specified parameters. The parameters are interpreted as the
	146	.B ASCII
	147	representations of the decimal values to place in the
	148	.B mt_op
	149	and
	150	.B mt_count
	151	fields of the structure used in the
	152	.B ioctl
	153	call. The return value is the
	154	.I count
	155	parameter when the operation is successful.
	156	.IP
	157	By issuing the
	158	.B I-1\en0\en
	159	command, a client will specify that he is using the VERSION 1 protocol.
	160	.IP
	161	For a VERSION 0 client, the
	162	.I operation
	163	parameter is the platform
	164	.B mt_op
	165	value (could be different if the client and the
	166	.B rmt
	167	server are on two different platforms). For a VERSION 1 client, the
	168	.I operation
	169	parameter is standardized as below:
	170	.RS
	171	.TP
	172	.B 0
	173	Issue a
	174	.B MTWEOF
	175	command (write
	176	.I count
	177	end-of-file records).
	178	.TP
	179	.B 1
	180	Issue a
	181	.B MTFSF
	182	command (forward space over
	183	.I count
	184	file marks).
	185	.TP
	186	.B 2
	187	Issue a
	188	.B MTBSF
	189	command (backward space over
	190	.I count
	191	file marks).
	192	.TP
	193	.B 3
	194	Issue a
	195	.B MTFSR
	196	command (forward space
	197	.I count
	198	inter-record gaps).
	199	.TP
	200	.B 4
	201	Issue a
	202	.B MTBSR
	203	command (backward space
	204	.I count
	205	inter-record gaps).
	206	.TP
	207	.B 5
	208	Issue a
	209	.B MTREW
	210	command (rewind).
	211	.TP
	212	.B 6
	213	Issue a
	214	.B MTOFFL
	215	command (rewind and put the drive offline).
	216	.TP
	217	.B 7
	218	Issue a
	219	.B MTNOP
	220	command (no operation, set status only).
	221	.RE
	222	.TP
	223	.B i\fIoperation\fR\en\fIcount\fR\en
	224	Perform an extended
	225	.B MTIOCOP
	226	.BR ioctl (2)
	227	command using the specified parameters. The parameters are interpreted as the
	228	.B ASCII
	229	representations of the decimal values to place in the
	230	.B mt_op
	231	and
	232	.B mt_count
	233	fields of the structure used in the
	234	.B ioctl
	235	call. The return value is the
	236	.I count
	237	parameter when the operation is successful. The possible operations are:
	238	.RS
	239	.TP
	240	.B 0
	241	Issue a
	242	.B MTCACHE
	243	command (switch cache on).
	244	.TP
	245	.B 1
	246	Issue a
	247	.B MTNOCACHE
	248	command (switch cache off).
	249	.TP
	250	.B 2
	251	Issue a
	252	.B MTRETEN
	253	command (retension the tape).
	254	.TP
	255	.B 3
	256	Issue a
	257	.B MTERASE
	258	command (erase the entire tape).
	259	.TP
	260	.B 4
	261	Issue a
	262	.B MTEOM
	263	command (position to end of media).
	264	.TP
	265	.B 5
	266	Issue a
	267	.B MTNBSF
	268	command (backward space count files to BOF).
	269	.RE
	270	.TP
	271	.B S
	272	Return the status of the open device, as obtained with a
	273	.B MTIOCGET
	274	.B ioctl
	275	call. If the operation was successful, an \(lqack\(rq is sent with the size
	276	of the status buffer, then the status buffer is sent (in binary, which is
	277	non-portable between different platforms).
	278	.TP
	279	.BI s sub-command
	280	This is a replacement for the previous
	281	.B S
	282	command, portable across different platforms. If the open device is a magnetic
	283	tape, return members of the magnetic tape status structure, as obtained with a
	284	.B MTIOCGET
	285	ioctl call. If the open device is not a magnetic tape, an error is returned. If
	286	the
	287	.B MTIOCGET
	288	operation was successful, the numerical value of the structure member is
	289	returned in decimal. The following sub commands are supported:
	290	.RS
	291	.TP
	292	.B T
	293	return the content of the structure member
	294	.B mt_type
	295	which contains the type of the magnetic tape device.
	296	.TP
	297	.B D
	298	return the content of the structure member
	299	.B mt_dsreg
	300	which contains the "drive status register".
	301	.TP
	302	.B E
	303	return the content of the structure member
	304	.B mt_erreg
	305	which contains the "error register". This structure member must be retrieved
	306	first because it is cleared after each
	307	.B MTIOCGET
	308	ioctl call.
	309	.TP
	310	.B R
	311	return the content of the structure member
	312	.B mt_resid
	313	which contains the residual count of the last I/O.
	314	.TP
	315	.B F
	316	return the content of the structure member
	317	.B mt_fileno
	318	which contains the file number of the current tape position.
	319	.TP
	320	.B B
	321	return the content of the structure member
	322	.B mt_blkno
	323	which contains the block number of the current tape position.
	324	.TP
	325	.B f
	326	return the content of the structure member
	327	.B mt_flags
	328	which contains MTF_ flags from the driver.
	329	.TP
	330	.B b
	331	return the content of the structure member
	332	.B mt_bf
	333	which contains the optimum blocking factor.
	334	.RE
	335	.PP
	336	Any other command causes
	337	.B rmt
	338	to exit.
	339	.SH DIAGNOSTICS
	340	All responses are of the form described above.
	341	.SH SEE ALSO
	342	.BR rcmd (3),
	343	.BR rexec (3),
	344	.I /usr/include/sys/mtio.h,
	345	.BR rdump (8),
	346	.BR rrestore (8)
	347	.SH BUGS
	348	People should be discouraged from using this for a remote file access protocol.
	349	.SH AUTHOR
	350	The
	351	.B dump/restore
	352	backup suit was ported to Linux's Second Extended File System by Remy Card
	353	<card@Linux.EU.Org>. He maintained the initial versions of
	354	.B dump
	355	(up and including 0.4b4, released in january 1997).
	356	.PP
	357	Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
	358	.SH AVAILABILITY
	359	The
	360	.B dump/restore
	361	backup suit is available from <http://dump.sourceforge.net>
	362	.SH HISTORY
	363	The
	364	.B rmt
	365	command appeared in 4.2BSD.