rmt(8c) rmt(8c)
Name
rmt - remote mass storage device protocol module
Syntax
/etc/rmt
Description
The program is used by the remote dump and restore programs to manipulate remote mass storage devices and files through an interprocess
communication 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 com-
mands have responses of an acknowledgement (ack) such as:
Anumber
In this example, number is an ASCII representation of a decimal number. Unsuccessful commands are responded to with the following:
Eerror-number
error-message
,
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 commands (a newline (
) 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 passing 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 opera-
tion 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 opera-
tion 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 premature 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 kilobytes), it is trun-
cated to the data buffer size. The program then performs the requested and responds with Acount-read
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 parameters. 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 Also
rcmd(3x), rexec(3x), mtio(4), rdump(8c), rrestore(8c)
rmt(8c)