dd(1) - c7

1DD(1)                            User Commands                           DD(1)
2
3
4

NAME

6       dd - convert and copy a file
7

SYNOPSIS

9       dd [OPERAND]...
10       dd OPTION
11

DESCRIPTION

13       Copy a file, converting and formatting according to the operands.
14
15       bs=BYTES
16              read and write up to BYTES bytes at a time
17
18       cbs=BYTES
19              convert BYTES bytes at a time
20
21       conv=CONVS
22              convert the file as per the comma separated symbol list
23
24       count=N
25              copy only N input blocks
26
27       ibs=BYTES
28              read up to BYTES bytes at a time (default: 512)
29
30       if=FILE
31              read from FILE instead of stdin
32
33       iflag=FLAGS
34              read as per the comma separated symbol list
35
36       obs=BYTES
37              write BYTES bytes at a time (default: 512)
38
39       of=FILE
40              write to FILE instead of stdout
41
42       oflag=FLAGS
43              write as per the comma separated symbol list
44
45       seek=N skip N obs-sized blocks at start of output
46
47       skip=N skip N ibs-sized blocks at start of input
48
49       status=LEVEL
50              The  LEVEL  of information to print to stderr; 'none' suppresses
51              everything but error messages,  'noxfer'  suppresses  the  final
52              transfer  statistics, 'progress' shows periodic transfer statis‐
53              tics
54
55       N and BYTES may be followed by the following multiplicative suffixes: c
56       =1, w =2, b =512, kB =1000, K =1024, MB =1000*1000, M =1024*1024, xM =M
57       GB =1000*1000*1000, G =1024*1024*1024, and so on for T, P, E, Z, Y.
58
59       Each CONV symbol may be:
60
61       ascii  from EBCDIC to ASCII
62
63       ebcdic from ASCII to EBCDIC
64
65       ibm    from ASCII to alternate EBCDIC
66
67       block  pad newline-terminated records with spaces to cbs-size
68
69       unblock
70              replace trailing spaces in cbs-size records with newline
71
72       lcase  change upper case to lower case
73
74       ucase  change lower case to upper case
75
76       sparse try to seek rather than write the output for NUL input blocks
77
78       swab   swap every pair of input bytes
79
80       sync   pad every input block with NULs  to  ibs-size;  when  used  with
81              block or unblock, pad with spaces rather than NULs
82
83       excl   fail if the output file already exists
84
85       nocreat
86              do not create the output file
87
88       notrunc
89              do not truncate the output file
90
91       noerror
92              continue after read errors
93
94       fdatasync
95              physically write output file data before finishing
96
97       fsync  likewise, but also write metadata
98
99       Each FLAG symbol may be:
100
101       append append  mode  (makes  sense  only  for output; conv=notrunc sug‐
102              gested)
103
104       direct use direct I/O for data
105
106       directory
107              fail unless a directory
108
109       dsync  use synchronized I/O for data
110
111       sync   likewise, but also for metadata
112
113       fullblock
114              accumulate full blocks of input (iflag only)
115
116       nonblock
117              use non-blocking I/O
118
119       noatime
120              do not update access time
121
122       nocache
123              discard cached data
124
125       noctty do not assign controlling terminal from file
126
127       nofollow
128              do not follow symlinks
129
130       count_bytes
131              treat 'count=N' as a byte count (iflag only)
132
133       skip_bytes
134              treat 'skip=N' as a byte count (iflag only)
135
136       seek_bytes
137              treat 'seek=N' as a byte count (oflag only)
138
139       Sending a USR1 signal to a running 'dd' process makes it print I/O sta‐
140       tistics to standard error and then resume copying.
141
142              $ dd if=/dev/zero of=/dev/null& pid=$!
143              $ kill -USR1 $pid; sleep 1; kill $pid
144
145              18335302+0  records  in  18335302+0 records out 9387674624 bytes
146              (9.4 GB) copied, 34.6279 seconds, 271 MB/s
147
148       Options are:
149
150       --help display this help and exit
151
152       --version
153              output version information and exit
154
155       GNU  coreutils  online  help:  <http://www.gnu.org/software/coreutils/>
156       Report dd translation bugs to <http://translationproject.org/team/>
157

AUTHOR

159       Written by Paul Rubin, David MacKenzie, and Stuart Kemp.
160

COPYRIGHT

162       Copyright  ©  2013  Free Software Foundation, Inc.  License GPLv3+: GNU
163       GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
164       This is free software: you are free  to  change  and  redistribute  it.
165       There is NO WARRANTY, to the extent permitted by law.
166

NAME

SYNOPSIS

DESCRIPTION

AUTHOR

COPYRIGHT

SEE ALSO