rmt
DESCRIPTION
Rmt is a program used by the remote dump and restore programs in manipu
lating a magnetic tape drive through an interprocess communication con
nection. Rmt is normally started up with an rexec(3) or rcmd(3) call.
The rmt program accepts requests specific to the manipulation of magnetic
tapes, performs the commands, then responds with a status indication.
All responses are in ASCII and in one of two forms. Successful commands
have responses of:
Anumber\n
Number is an ASCII representation of a decimal number. Unsuccessful com
mands are responded to with:
Eerror-number\nerror-message\n
Error-number is one of the possible error numbers described in intro(2)
and error-message is the corresponding error string as printed from a
call to perror(3). 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 `\n' indicates that a
newline should be supplied:
Odevice\nmode\n
Open the specified device using the indicated mode. Device is a
full pathname and mode is an ASCII representation of a decimal
number suitable for passing to open(2). If a device had already
been opened, it is closed before a new open is performed.
Cdevice\n
Close the currently open device. The device specified is ig
nored.
Lwhence\noffset\n
Perform an lseek(2) operation using the specified parameters.
The response value is that returned from the lseek call.
Wcount\n
Write data onto the open device. Rmt reads count bytes from the
connection, aborting if a premature end-of-file is encountered.
The response value is that returned from the write(2) call.
Rcount\n
Read count bytes of data from the open device. If count exceeds
the size of the data buffer (10 kilobytes), it is truncated to
the data buffer size. Rmt then performs the requested read(2)
and responds with Acount-read\n if the read was successful; oth
erwise an error in the standard format is returned. If the read
was successful, the data read is then sent.
Ioperation\ncount\n
Perform a MTIOCOP ioctl(2) command using the specified parame
ters. The parameters are interpreted as the ASCII representa
Any other command causes rmt to exit.
DIAGNOSTICS
All responses are of the form described above.
SEE ALSO
rcmd(3), rexec(3), mtio(4), rdump(8), rrestore(8)
BUGS
People should be discouraged from using this for a remote file access
protocol.
AUTHOR
The dump/restore backup suit was ported to Linux's Second Extended File
System by Remy Card <card@Linux.EU.Org>. He maintained the initial ver
sions of dump (up and including 0.4b4, released in january 1997).
Starting with 0.4b5, the new maintainer is Stelian Pop
<pop@noos.fr>.
AVAILABILITY
The dump/restore backup suit is available from
http://dump.sourceforge.net
HISTORY
The rmt command appeared in 4.2BSD.
rmt 0.4b22 May 12, 2001 2
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