rmt.8c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 8C 代码 · 共 184 行

.\" SCCSID: @(#)rmt.8c	8.1	9/11/90
.TH rmt 8c 
.SH Name
rmt \- remote mass storage device protocol module
.SH Syntax
.B /etc/rmt
.SH Description
.NXR "rmt program"
.NXR "file system" "copying across network"
.NXS "remote mass storage protocol module" "rmt program"
.NXA "rdump command" "rmt program"
The
.PN rmt
program is used by the remote dump and restore programs
to manipulate remote mass storage devices and files
through an interprocess
communication connection.
The 
.PN rmt
program is normally started with an
.MS rexec 3x
or
.MS rcmd 3x
call.
.PP
The 
.PN rmt
program remotely ties its standard input and output to a socket,
accepts commands that manipulate
remote devices or files, performs the commands, and then responds with
a status indication.  All commands and responses are in ASCII and in
one of two forms. 
Successful commands have responses of
an acknowledgement (ack) such as:
.PP
.ti +0.5i
\fBA\fInumber\fR\en
.PP
In this example, 
.I number
is an ASCII representation of a decimal number.
Unsuccessful commands are responded to with the following:
.PP
.ti +0.5i
\fBE\fIerror-number\fR\en\fIerror-message\fR\en,
.PP
In this example, 
.I error-number
is one of the possible error
numbers described in
.MS intro 2
and
.I error-message
is the corresponding error string as printed
from a call to
.MS perror 3 .
The protocol is comprised of the
following commands (a newline (\\n)
is present between each token):
.NXR "rmt program" "commands"
.TP 17
\fBO \fIdevice mode\fR
Open the specified 
.I device
using the indicated
.IR mode .
The 
.I device
is a full pathname and
.I mode
is an ASCII representation of a decimal
number suitable for passing to
.MS open 2 .
If a device had already been opened, it is
closed before a new open is performed.
Device can be a regular file.
.TP 17
\fBC \fIdevice\fR
Close the currently open device or file.  The
.I device
specified is ignored.
.TP 17
.B D
Returns generic device information for the open device. A
DEVIOCGET
.MS ioctl 2 
call is performed and the data returned. If the operation
is successful, an ``ack'' is sent with the size of the information
buffer.
.TP 17
\fBL \fIwhence offset\fR
Perform an
.MS seek 2
operation using the specified parameters.
The response value is that returned from the
.PN lseek
call.
.TP 17
.B P
Returns disk partition information of the open device. A
DIOCDGTPT
.MS ioctl 2
call is performed and the data returned. If the operation
is successful, an ``ack'' is sent with the size of the information
buffer.
.TP 17
\fBT \fIfilename\fR
Returns file status information for the specified file. A
.MS stat 2
call is performed and the data returned. If the operation
is successful, an ``ack'' is sent with the size of the information
buffer.
.TP 17
\fBW \fIcount\fR
Write data onto the open device.
The
.PN rmt
program reads
.I count
bytes from the connection, aborting if
a premature end-of-file is encountered.
The response value is that returned from
the
.MS write 2
call.
If the operation was successful, an ``ack'' is sent containing
the number of bytes written.
.TP 17
\fBR \fIcount\fR
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.
The
.PN rmt
program then performs the requested 
.MS read 2
and responds with 
\fBA\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 17
\fBI \fIoperation count\fR
Perform a MTIOCTOP 
.MS ioctl 2
command using the specified parameters.
The parameters are interpreted as the
ASCII representations of the decimal values
to place in the 
.I mt_op
and
.I mt_count
fields of the structure used in the
.PN ioctl
call.  The return value is the
.I count
parameter when the operation is successful.
.TP 17
.B S
Return the status of the open device, as
obtained with a MTIOCGET 
.PN ioctl
call.  If the operation was successful,
an ``ack'' is sent with the size of the
status buffer, then the status buffer is
sent (in binary).
.PP
Any other command causes 
.PN rmt
to exit.
.SH Restrictions
.NXR "rmt program" "restricted"
Do not use 
.PN rmt
for a remote file access protocol.
.SH Diagnostics
All responses are of the form described above.
.SH See Also
rcmd(3x), rexec(3x), mtio(4), rdump(8c), rrestore(8c)