[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. 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.
.\"
.\"     $Id: rmt.8.in,v 1.9 2002/07/24 14:12:01 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. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" $Id: rmt.8.in,v 1.9 2002/07/24 14:12:01 stelian Exp $
	33	.\"
	34	.TH RMT 8 "version __VERSION__ of __DATE__" BSD "System management commands"
	35	.SH NAME
	36	rmt \- remote magtape protocol module
	37	.SH SYNOPSIS
	38	.B rmt
	39	.SH DESCRIPTION
	40	.B Rmt
	41	is a program used by the remote
	42	.BR dump (8),
	43	.BR restore (8)
	44	or
	45	.BR tar (1)
	46	programs in manipulating a magnetic tape drive through an interprocess
	47	communication connection.
	48	.B Rmt
	49	is normally started up with an
	50	.BR rexec (3)
	51	or
	52	.BR rcmd (3)
	53	call.
	54	.PP
	55	The
	56	.B rmt
	57	program accepts requests specific to the manipulation of magnetic tapes,
	58	performs the commands, then responds with a status indication. All responses
	59	are in
	60	.B ASCII
	61	and in one of the following two forms.
	62	.PP
	63	Successful commands have responses of:
	64	.RS
	65	.B A\fInumber\fR\en
	66	.RE
	67	.PP
	68	where
	69	.I number
	70	is an
	71	.B ASCII
	72	representation of a decimal number.
	73	.PP
	74	Unsuccessful commands are responded to with:
	75	.RS
	76	.B E\fIerror-number\fR\en\fIerror-message\fR\en
	77	.RE
	78	.PP
	79	where
	80	.I error-number
	81	is one of the possible error numbers described in
	82	.BR intro (2)
	83	and
	84	.I error-message
	85	is the corresponding error string as printed from a call to
	86	.BR perror (3).
	87	.PP
	88	The protocol is comprised of the following commands, which are sent as
	89	indicated - no spaces are supplied between the command and its arguments, or
	90	between its arguments, and \en indicates that a newline should be supplied:
	91	.TP
	92	.B O\fIdevice\fR\en\fImode\fR\en
	93	Open the specified
	94	.I device
	95	using the indicated
	96	.IR mode .
	97	.I Device
	98	is a full pathname and
	99	.I mode
	100	is an
	101	.B ASCII
	102	representation of a decimal number suitable for passing to
	103	.BR open (2).
	104	If a device had already been opened, it is closed before a new open is
	105	performed.
	106	.TP
	107	.B C\fIdevice\fR\en
	108	Close the currently open device. The
	109	.I device
	110	specified is ignored.
	111	.TP
	112	.B L\fIwhence\fR\en\fIoffset\fR\en
	113	Perform an
	114	.BR lseek (2)
	115	operation using the specified parameters. The response value is that returned
	116	from the
	117	.B lseek
	118	call.
	119	.TP
	120	.B W\fIcount\fR\en
	121	Write data onto the open device.
	122	.B Rmt
	123	reads
	124	.I count
	125	bytes from the connection, aborting if a premature end-of-file is encountered.
	126	The response value is that returned from the
	127	.BR write (2)
	128	call.
	129	.TP
	130	.B R\fIcount\fR\en
	131	Read
	132	.I count
	133	bytes of data from the open device. If
	134	.I count
	135	exceeds the size of the data buffer (10 kilobytes), it is truncated to the
	136	data buffer size.
	137	.B Rmt
	138	then performs the requested
	139	.BR read (2)
	140	and responds with
	141	.B A\fIcount-read\fR\en
	142	if the read was successful; otherwise an error in the standard format is
	143	returned. If the read was successful, the data read is then sent.
	144	.TP
	145	.B I\fIoperation\fR\en\fIcount\fR\en
	146	Perform a
	147	.B MTIOCOP
	148	.BR ioctl (2)
	149	command using the specified parameters. The parameters are interpreted as the
	150	.B ASCII
	151	representations of the decimal values to place in the
	152	.B mt_op
	153	and
	154	.B mt_count
	155	fields of the structure used in the
	156	.B ioctl
	157	call. The return value is the
	158	.I count
	159	parameter when the operation is successful.
	160	.IP
	161	By issuing the
	162	.B I-1\en0\en
	163	command, a client will specify that he is using the VERSION 1 protocol.
	164	.IP
	165	For a VERSION 0 client, the
	166	.I operation
	167	parameter is the platform
	168	.B mt_op
	169	value (could be different if the client and the
	170	.B rmt
	171	server are on two different platforms). For a VERSION 1 client, the
	172	.I operation
	173	parameter is standardized as below:
	174	.RS
	175	.TP
	176	.B 0
	177	Issue a
	178	.B MTWEOF
	179	command (write
	180	.I count
	181	end-of-file records).
	182	.TP
	183	.B 1
	184	Issue a
	185	.B MTFSF
	186	command (forward space over
	187	.I count
	188	file marks).
	189	.TP
	190	.B 2
	191	Issue a
	192	.B MTBSF
	193	command (backward space over
	194	.I count
	195	file marks).
	196	.TP
	197	.B 3
	198	Issue a
	199	.B MTFSR
	200	command (forward space
	201	.I count
	202	inter-record gaps).
	203	.TP
	204	.B 4
	205	Issue a
	206	.B MTBSR
	207	command (backward space
	208	.I count
	209	inter-record gaps).
	210	.TP
	211	.B 5
	212	Issue a
	213	.B MTREW
	214	command (rewind).
	215	.TP
	216	.B 6
	217	Issue a
	218	.B MTOFFL
	219	command (rewind and put the drive offline).
	220	.TP
	221	.B 7
	222	Issue a
	223	.B MTNOP
	224	command (no operation, set status only).
	225	.RE
	226	.TP
	227	.B i\fIoperation\fR\en\fIcount\fR\en
	228	Perform an extended
	229	.B MTIOCOP
	230	.BR ioctl (2)
	231	command using the specified parameters. The parameters are interpreted as the
	232	.B ASCII
	233	representations of the decimal values to place in the
	234	.B mt_op
	235	and
	236	.B mt_count
	237	fields of the structure used in the
	238	.B ioctl
	239	call. The return value is the
	240	.I count
	241	parameter when the operation is successful. The possible operations are:
	242	.RS
	243	.TP
	244	.B 0
	245	Issue a
	246	.B MTCACHE
	247	command (switch cache on).
	248	.TP
	249	.B 1
	250	Issue a
	251	.B MTNOCACHE
	252	command (switch cache off).
	253	.TP
	254	.B 2
	255	Issue a
	256	.B MTRETEN
	257	command (retension the tape).
	258	.TP
	259	.B 3
	260	Issue a
	261	.B MTERASE
	262	command (erase the entire tape).
	263	.TP
	264	.B 4
	265	Issue a
	266	.B MTEOM
	267	command (position to end of media).
	268	.TP
	269	.B 5
	270	Issue a
	271	.B MTNBSF
	272	command (backward space count files to BOF).
	273	.RE
	274	.TP
	275	.B S
	276	Return the status of the open device, as obtained with a
	277	.B MTIOCGET
	278	.B ioctl
	279	call. If the operation was successful, an \(lqack\(rq is sent with the size
	280	of the status buffer, then the status buffer is sent (in binary, which is
	281	non-portable between different platforms).
	282	.TP
	283	.BI s sub-command
	284	This is a replacement for the previous
	285	.B S
	286	command, portable across different platforms. If the open device is a magnetic
	287	tape, return members of the magnetic tape status structure, as obtained with a
	288	.B MTIOCGET
	289	ioctl call. If the open device is not a magnetic tape, an error is returned. If
	290	the
	291	.B MTIOCGET
	292	operation was successful, the numerical value of the structure member is
	293	returned in decimal. The following sub commands are supported:
	294	.RS
	295	.TP
	296	.B T
	297	return the content of the structure member
	298	.B mt_type
	299	which contains the type of the magnetic tape device.
	300	.TP
	301	.B D
	302	return the content of the structure member
	303	.B mt_dsreg
	304	which contains the "drive status register".
	305	.TP
	306	.B E
	307	return the content of the structure member
	308	.B mt_erreg
	309	which contains the "error register". This structure member must be retrieved
	310	first because it is cleared after each
	311	.B MTIOCGET
	312	ioctl call.
	313	.TP
	314	.B R
	315	return the content of the structure member
	316	.B mt_resid
	317	which contains the residual count of the last I/O.
	318	.TP
	319	.B F
	320	return the content of the structure member
	321	.B mt_fileno
	322	which contains the file number of the current tape position.
	323	.TP
	324	.B B
	325	return the content of the structure member
	326	.B mt_blkno
	327	which contains the block number of the current tape position.
	328	.TP
	329	.B f
	330	return the content of the structure member
	331	.B mt_flags
	332	which contains MTF_ flags from the driver.
	333	.TP
	334	.B b
	335	return the content of the structure member
	336	.B mt_bf
	337	which contains the optimum blocking factor.
	338	.RE
	339	.PP
	340	Any other command causes
	341	.B rmt
	342	to exit.
	343	.SH DIAGNOSTICS
	344	All responses are of the form described above.
	345	.SH SEE ALSO
	346	.BR rcmd (3),
	347	.BR rexec (3),
	348	.I /usr/include/sys/mtio.h,
	349	.BR rdump (8),
	350	.BR rrestore (8)
	351	.SH BUGS
	352	People should be discouraged from using this for a remote file access protocol.
	353	.SH AUTHOR
	354	The
	355	.B dump/restore
	356	backup suit was ported to Linux's Second Extended File System by Remy Card
	357	<card@Linux.EU.Org>. He maintained the initial versions of
	358	.B dump
	359	(up and including 0.4b4, released in january 1997).
	360	.PP
	361	Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
	362	.SH AVAILABILITY
	363	The
	364	.B dump/restore
	365	backup suit is available from <http://dump.sourceforge.net>
	366	.SH HISTORY
	367	The
	368	.B rmt
	369	command appeared in 4.2BSD.