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1.1 root 1: .TH DD 1 "18 January 1983"
2: .UC 4
3: .SH NAME
4: dd \- convert and copy a file
5: .SH SYNOPSIS
6: .B dd
7: [option=value] ...
8: .SH DESCRIPTION
9: .I Dd
10: copies the specified input file
11: to the specified output with
12: possible conversions.
13: The standard input and output are used by default.
14: The input and output block size may be
15: specified to take advantage of raw physical I/O.
16: .PP
17: .br
18: .ns
19: .TP 15
20: .I option
21: .I values
22: .br
23: .ns
24: .TP
25: if=
26: input file name; standard input is default
27: .br
28: .ns
29: .TP
30: of=
31: output file name; standard output is default
32: .br
33: .ns
34: .TP
35: .RI ibs= n
36: input block size
37: .I n
38: bytes (default 512)
39: .br
40: .ns
41: .TP
42: .RI obs= n
43: output block size (default 512)
44: .br
45: .ns
46: .TP
47: .RI bs= n
48: set both input and output block size,
49: superseding
50: .I ibs
51: and
52: .I obs;
53: also, if no conversion is specified,
54: it is particularly efficient since no copy need be done
55: .br
56: .ns
57: .TP
58: .RI cbs= n
59: conversion buffer size
60: .br
61: .ns
62: .TP
63: .RI skip= n
64: skip
65: .IR n ""
66: input records before starting copy
67: .br
68: .ns
69: .TP
70: .RI files= n
71: copy
72: .I n
73: input files before terminating (makes sense only
74: where input is a magtape or similar device).
75: .br
76: .ns
77: .TP
78: .RI seek= n
79: seek
80: .I n
81: records from beginning of output file before copying
82: .br
83: .ns
84: .TP
85: count=\fIn\fR
86: copy only
87: .IR n ""
88: input records
89: .br
90: .ns
91: .TP
92: conv=ascii
93: .ds h \h'\w'conv='u'
94: convert EBCDIC to ASCII
95: .br
96: .ns
97: .IP \*hebcdic
98: convert ASCII to EBCDIC
99: .br
100: .ns
101: .IP \*hibm
102: slightly different map of ASCII to EBCDIC
103: .br
104: .ns
105: .IP \*hblock
106: convert variable length records to fixed length
107: .br
108: .ns
109: .IP \*hunblock
110: convert fixed length records to variable length
111: .br
112: .ns
113: .IP \*hlcase
114: map alphabetics to lower case
115: .br
116: .ns
117: .IP \*hucase
118: map alphabetics to upper case
119: .br
120: .ns
121: .IP \*hswab
122: swap every pair of bytes
123: .br
124: .ns
125: .IP \*hnoerror
126: do not stop processing on an error
127: .br
128: .ns
129: .IP \*hsync
130: pad every input record to
131: .I ibs
132: .br
133: .ns
134: .IP "\*h... , ..."
135: several comma-separated conversions
136: .PP
137: .fi
138: Where sizes are specified,
139: a number of bytes is expected.
140: A number may end with
141: .B "k, b"
142: or
143: .B w
144: to specify multiplication by
145: 1024, 512, or 2 respectively;
146: a pair of numbers may be separated by
147: .B x
148: to indicate a product. The maximum
149: limit for the block size is 32k.
150: .PP
151: .I Cbs
152: is used only if
153: .I ascii,
154: .I unblock,
155: .I ebcdic,
156: .I ibm,
157: or
158: .I block
159: conversion is specified.
160: In the first two cases,
161: .I cbs
162: characters are placed into the conversion buffer, any specified
163: character mapping is done,
164: trailing blanks trimmed and new-line added
165: before sending the line to the output.
166: In the latter three cases, characters are read into the
167: conversion buffer, and blanks added
168: to make up an
169: output record of size
170: .IR cbs .
171: .PP
172: After completion,
173: .I dd
174: reports the number of whole and partial input and output
175: blocks.
176: .PP
177: For example, to read an EBCDIC tape blocked ten 80-byte
178: EBCDIC card images per record into the ASCII file
179: .I x:
180: .IP
181: .nf
182: dd if=/dev/rmt0 of=x ibs=800 cbs=80 conv=ascii,lcase
183: .fi
184: .PP
185: Note the use of raw magtape.
186: .I Dd
187: is especially suited to I/O on the raw
188: physical devices because it allows reading
189: and writing in arbitrary record sizes.
190: .SH "SEE ALSO"
191: cp(1), tr(1)
192: .SH DIAGNOSTICS
193: f+p records in(out): numbers of full and partial records read(written)
194: .SH BUGS
195: The ASCII/EBCDIC conversion tables are
196: taken
197: from the 256 character standard in
198: the CACM Nov, 1968.
199: The `ibm' conversion, while less blessed as a standard,
200: corresponds better to certain IBM print train conventions.
201: There is no universal solution.
202: .br
203: One must specify ``conv=noerror,sync'' when copying
204: raw disks with bad sectors to insure
205: .I dd
206: stays synchronized.
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