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1 perry 1 ----
2 __NAME__
3
4
5 rmt - remote magtape protocol module
6 __SYNOPSIS__
7
8
9 rmt
10 __DESCRIPTION__
11
12
13 Rmt is a program used by tar, cpio, mt, and the remote dump
14 and restore programs in manipulating a magnetic tape drive
15 through an interprocess communication connection. Rmt is
16 normally started up with an rexec(3) or
17 rcmd(3) call or the rsh(1)
18 command.
19
20
21 The rmt program accepts requests specific to the manipula- tion 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:
22
23
24 __A__numbern
25
26
27 Number is an ASCII representation of a
28 decimal number. Unsuccessful commands are responded to
29 with:
30 __ E__error-numbernerror-message
31 n
32 Error-number is one of the possible error numbers
33 described in intro(2) and error-message is the
34 corresponding error string as printed from a call to
35 perror(3). The protocol is comprised of the
36 following commands, which are sent as indi- cated - no
37 spaces are supplied between the command and its arguments,
38 or between its arguments, and n indicates that a
39 newline should be supplied:
40 __ O__devicenmoden
41
42
43 Open the specified deviceusing the indicatedmode.Deviceis a full pathname and modeis anASCIIrepresentation of a decimal number suitable forpassing to open(2).If a device had already been opened, it is closed before a new open is performed.
44
45
46 __C__devicen
47 Close the currently open device. The devicespecified is
48 ignored.
49
50
51 __L__offsetn
52 whencen
53 Perform an lseek(2) operation using the specified
54 parameters. The response value is that returned from the
55 lseek call.
56
57
58 __W__countn
59 Write data onto the open device. Rmt reads count bytes from
60 the connection, aborting if a premature end-of-file is
61 encountered. The response value is that returned from the
62 write(2) call.
63
64
65 __R__countn
66 Read count bytes of data from the open device. If count
67 exceeds the size of the data buffer (10 kilo- bytes), it is
68 truncated to the data buffer size. rmt then performs the
69 requested read(2) and responds with
70 __A__count-readn if the read was successful; otherwise an
71 error in the standard format is returned. If the read was
72 successful, the data read is then sent.
73
74
75 __I__operationncountn
76 Perform a MTIOCOP ioctl(2) command using the speci-
77 fied parameters. The parameters are interpreted as the
78 ASCII representations of the decimal values
79 to place in the mt_op and mt_count fields of the struc- ture
80 used in the ioctl call. The return value is the
81 count parameter when the operation is
82 successful.
83
84
85 __S__
86 Return the status of the open device, as obtained with a
87 MTIOCGET ioctl call. If the operation was
88 successful, an ``ack'' is sent with the size of the status
89 buffer, then the status buffer is sent (in
90 binary).
91
92
93 Any other command causes rmt to exit.
94
95
96 __DIAGNOSTICS__
97
98
99 All responses are of the form described above.
100 __SEE ALSO__
101
102
103 tar(1), cpio(1), mt(1),
104 rsh(1), rcmd(3), rexec(3),
105 mtio(4), rdump(8),
106 rrestore(8)
107 __BUGS__
108
109
110 People should be discouraged from using this for a remote
111 file access protocol.
112 __HISTORY__
113
114
115 The rmt command appeared in 4.2 BSD
116 .
117
118
2 perry 119 4.2 Berkeley !DistributionDecember 11, 1993 1
1 perry 120 ----
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