1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)rmt.8 8.3 (Berkeley) 06/01/94 7.\" 8.Dd 9.Dt RMT 8 10.Os BSD 4.2 11.Sh NAME 12.Nm rmt 13.Nd remote magtape protocol module 14.Sh SYNOPSIS 15.Nm rmt 16.Sh DESCRIPTION 17.Nm Rmt 18is a program used by the remote dump and restore programs 19in manipulating a magnetic tape drive through an interprocess 20communication connection. 21.Nm Rmt 22is normally started up with an 23.Xr rexec 3 24or 25.Xr rcmd 3 26call. 27.Pp 28The 29.Nm rmt 30program accepts requests specific to the manipulation of 31magnetic tapes, performs the commands, then responds with 32a status indication. All responses are in 33.Tn ASCII 34and in 35one of two forms. 36Successful commands have responses of: 37.Bd -filled -offset indent 38.Sm off 39.Sy A Ar number No \en 40.Sm on 41.Ed 42.Pp 43.Ar Number 44is an 45.Tn ASCII 46representation of a decimal number. 47Unsuccessful commands are responded to with: 48.Bd -filled -offset indent 49.Sm off 50.Xo Sy E Ar error-number 51.No \en Ar error-message 52.No \en 53.Xc 54.Sm on 55.Ed 56.Pp 57.Ar Error-number 58is one of the possible error 59numbers described in 60.Xr intro 2 61and 62.Ar error-message 63is the corresponding error string as printed 64from a call to 65.Xr perror 3 . 66The protocol is comprised of the 67following commands, which are sent as indicated - no spaces are supplied 68between the command and its arguments, or between its arguments, and 69.Ql \en 70indicates that a newline should be supplied: 71.Bl -tag -width Ds 72.Sm off 73.It Xo Sy \&O Ar device 74.No \en Ar mode No \en 75.Xc 76Open the specified 77.Ar device 78using the indicated 79.Ar mode . 80.Ar Device 81is a full pathname and 82.Ar mode 83is an 84.Tn ASCII 85representation of a decimal 86number suitable for passing to 87.Xr open 2 . 88If a device had already been opened, it is 89closed before a new open is performed. 90.It Xo Sy C Ar device No \en 91.Xc 92Close the currently open device. The 93.Ar device 94specified is ignored. 95.It Xo Sy L 96.Ar whence No \en 97.Ar offset No \en 98.Xc 99.Sm on 100Perform an 101.Xr lseek 2 102operation using the specified parameters. 103The response value is that returned from the 104.Xr lseek 105call. 106.Sm off 107.It Sy W Ar count No \en 108.Sm on 109Write data onto the open device. 110.Nm Rmt 111reads 112.Ar count 113bytes from the connection, aborting if 114a premature end-of-file is encountered. 115The response value is that returned from 116the 117.Xr write 2 118call. 119.Sm off 120.It Sy R Ar count No \en 121.Sm on 122Read 123.Ar count 124bytes of data from the open device. 125If 126.Ar count 127exceeds the size of the data buffer (10 kilobytes), it is 128truncated to the data buffer size. 129.Nm rmt 130then performs the requested 131.Xr read 2 132and responds with 133.Sm off 134.Sy A Ar count-read No \en 135.Sm on 136if the read was 137successful; otherwise an error in the 138standard format is returned. If the read 139was successful, the data read is then sent. 140.Sm off 141.It Xo Sy I Ar operation 142.No \en Ar count No \en 143.Xc 144.Sm on 145Perform a 146.Dv MTIOCOP 147.Xr ioctl 2 148command using the specified parameters. 149The parameters are interpreted as the 150.Tn ASCII 151representations of the decimal values 152to place in the 153.Ar mt_op 154and 155.Ar mt_count 156fields of the structure used in the 157.Xr ioctl 158call. The return value is the 159.Ar count 160parameter when the operation is successful. 161.ne 1i 162.It Sy S 163Return the status of the open device, as 164obtained with a 165.Dv MTIOCGET 166.Xr ioctl 167call. If the operation was successful, 168an ``ack'' is sent with the size of the 169status buffer, then the status buffer is 170sent (in binary). 171.El 172.Sm on 173.Pp 174Any other command causes 175.Nm rmt 176to exit. 177.Sh DIAGNOSTICS 178All responses are of the form described above. 179.Sh SEE ALSO 180.Xr rcmd 3 , 181.Xr rexec 3 , 182.Xr mtio 4 , 183.Xr rdump 8 , 184.Xr rrestore 8 185.Sh BUGS 186People should be discouraged from using this for a remote 187file access protocol. 188.Sh HISTORY 189The 190.Nm 191command appeared in 192.Bx 4.2 . 193