rmt(8c)rmt(8c)Namermt - remote mass storage device protocol module
Syntax
/etc/rmt
Description
The program is used by the remote dump and restore programs to manipu‐
late remote mass storage devices and files through an interprocess com‐
munication connection. The program is normally started with an or
call.
The 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:
Anumber\n
In this example, number is an ASCII representation of a decimal number.
Unsuccessful commands are responded to with the following:
Eerror-number\nerror-message\n,
In this example, error-number is one of the possible error numbers
described in and error-message is the corresponding error string as
printed from a call to The protocol is comprised of the following com‐
mands (a newline (\n) is present between each token):
O device mode Open the specified device using the indicated mode.
The device is a full pathname and mode is an ASCII
representation of a decimal number suitable for pass‐
ing to If a device had already been opened, it is
closed before a new open is performed. Device can be
a regular file.
C device Close the currently open device or file. The device
specified is ignored.
D Returns generic device information for the open
device. A DEVIOCGET call is performed and the data
returned. If the operation is successful, an ``ack''
is sent with the size of the information buffer.
L whence offset Perform an operation using the specified parameters.
The response value is that returned from the call.
P Returns disk partition information of the open device.
A DIOCDGTPT call is performed and the data returned.
If the operation is successful, an ``ack'' is sent
with the size of the information buffer.
T filename Returns file status information for the specified
file. A call is performed and the data returned. If
the operation is successful, an ``ack'' is sent with
the size of the information buffer.
W count Write data onto the open device. The program reads
count bytes from the connection, aborting if a prema‐
ture end-of-file is encountered. The response value
is that returned from the call. If the operation was
successful, an ``ack'' is sent containing the number
of bytes written.
R count Read count bytes of data from the open device. If
count exceeds the size of the data buffer (10 kilo‐
bytes), it is truncated to the data buffer size. The
program then performs the requested and responds with
Acount-read\n 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.
I operation count
Perform a MTIOCTOP command using the specified parame‐
ters. The parameters are interpreted as the ASCII
representations of the decimal values to place in the
mt_op and mt_count fields of the structure used in the
call. The return value is the count parameter when
the operation is successful.
S Return the status of the open device, as obtained with
a MTIOCGET 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).
Any other command causes to exit.
Restrictions
Do not use for a remote file access protocol.
Diagnostics
All responses are of the form described above.
See Alsorcmd(3x), rexec(3x), mtio(4), rdump(8c), rrestore(8c)rmt(8c)
