1DD(1)                            User Commands                           DD(1)
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NAME

6       dd - convert and copy a file
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SYNOPSIS

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

13       Copy a file, converting and formatting according to the operands.
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15       bs=BYTES
16              force ibs=BYTES and obs=BYTES
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18       cbs=BYTES
19              convert BYTES bytes at a time
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21       conv=CONVS
22              convert the file as per the comma separated symbol list
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24       count=BLOCKS
25              copy only BLOCKS input blocks
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27       ibs=BYTES
28              read BYTES bytes at a time
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30       if=FILE
31              read from FILE instead of stdin
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33       iflag=FLAGS
34              read as per the comma separated symbol list
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36       obs=BYTES
37              write BYTES bytes at a time
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39       of=FILE
40              write to FILE instead of stdout
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42       oflag=FLAGS
43              write as per the comma separated symbol list
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45       seek=BLOCKS
46              skip BLOCKS obs-sized blocks at start of output
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48       skip=BLOCKS
49              skip BLOCKS ibs-sized blocks at start of input
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51       status=noxfer
52              suppress transfer statistics
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54       BLOCKS  and  BYTES may be followed by the following multiplicative suf‐
55       fixes: xM M, c 1, w 2,  b  512,  kB  1000,  K  1024,  MB  1000*1000,  M
56       1024*1024,  GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E,
57       Z, Y.
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59       Each CONV symbol may be:
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61       ascii  from EBCDIC to ASCII
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63       ebcdic from ASCII to EBCDIC
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65       ibm    from ASCII to alternate EBCDIC
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67       block  pad newline-terminated records with spaces to cbs-size
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69       unblock
70              replace trailing spaces in cbs-size records with newline
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72       lcase  change upper case to lower case
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74       nocreat
75              do not create the output file
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77       excl   fail if the output file already exists
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79       notrunc
80              do not truncate the output file
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82       ucase  change lower case to upper case
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84       swab   swap every pair of input bytes
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86       noerror
87              continue after read errors
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89       sync   pad every input block with NULs  to  ibs-size;  when  used  with
90              block or unblock, pad with spaces rather than NULs
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92       fdatasync
93              physically write output file data before finishing
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95       fsync  likewise, but also write metadata
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97       Each FLAG symbol may be:
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99       append append  mode  (makes  sense  only  for output; conv=notrunc sug‐
100              gested)
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102       direct use direct I/O for data
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104              directory fail unless a directory dsync     use synchronized I/O
105              for data sync      likewise, but also for metadata nonblock  use
106              non-blocking I/O noatime   do  not  update  access  time  noctty
107              do  not  assign  controlling terminal from file nofollow  do not
108              follow symlinks
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110       Sending a USR1 signal to a running `dd' process makes it print I/O sta‐
111       tistics to standard error and then resume copying.
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113              $ dd if=/dev/zero of=/dev/null& pid=$!
114              $ kill -USR1 $pid; sleep 1; kill $pid
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116              18335302+0  records  in  18335302+0 records out 9387674624 bytes
117              (9.4 GB) copied, 34.6279 seconds, 271 MB/s
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119       Options are:
120
121       --help display this help and exit
122
123       --version
124              output version information and exit
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AUTHOR

127       Written by Paul Rubin, David MacKenzie, and Stuart Kemp.
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REPORTING BUGS

130       Report bugs to <bug-coreutils@gnu.org>.
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133       Copyright © 2007 Free Software Foundation, Inc.
134       This is free software.  You may redistribute copies  of  it  under  the
135       terms       of       the      GNU      General      Public      License
136       <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY,  to  the
137       extent permitted by law.
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SEE ALSO

140       The  full  documentation  for dd is maintained as a Texinfo manual.  If
141       the info and dd programs are properly installed at your site, the  com‐
142       mand
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144              info dd
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146       should give you access to the complete manual.
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150GNU coreutils 6.9                 March 2008                             DD(1)
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