NAME    [Toc]    [Back]

     rmt - remote magtape protocol module

SYNOPSIS    [Toc]    [Back]

     rmt

DESCRIPTION    [Toc]    [Back]

     rmt is a program used by the remote dump  and  restore  programs in manipulating
  a magnetic tape drive through an interprocess communication connection.
  rmt is normally started  up  with  an  rcmd(3)  or
rcmdsh(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

     number is an ASCII representation of a decimal number.   Unsuccessful commands
 are responded to with:

           Eerror-numbererror-message

     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 `0 indicates that a
     newline should be supplied:

     Odevicemode
             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
             Close the currently open device.  The device  specified is ignored.


     Loffsetwhence
             Perform  an  lseek(2)  operation using the specified
parameters.
             The response value is that returned from  the  lseek
call.

     Wcount
             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
             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-readif the read was successful; otherwise
 an error in the standard format is  returned.
If the read
             was successful, the data read is then sent.

     Ioperationcount
             Perform an MTIOCOP ioctl(2) 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  ioctl()  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
             ioctl(2)  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 rmt to exit.

DIAGNOSTICS    [Toc]    [Back]

     All responses are of the form described above.

SEE ALSO    [Toc]    [Back]

     rcmd(3), rcmdsh(3), mtio(4), rdump(8), rrestore(8)

HISTORY    [Toc]    [Back]

     The rmt command appeared in 4.2BSD.

BUGS    [Toc]    [Back]

     People tempted to use this for a remote file access protocol
are discouraged.


OpenBSD     3.6                          March      16,      1991