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              read and write up to BYTES bytes at a time (default: 512); over‐
17              rides ibs and obs
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19       cbs=BYTES
20              convert BYTES bytes at a time
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22       conv=CONVS
23              convert the file as per the comma separated symbol list
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25       count=N
26              copy only N input blocks
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28       ibs=BYTES
29              read up to BYTES bytes at a time (default: 512)
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31       if=FILE
32              read from FILE instead of stdin
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34       iflag=FLAGS
35              read as per the comma separated symbol list
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37       obs=BYTES
38              write BYTES bytes at a time (default: 512)
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40       of=FILE
41              write to FILE instead of stdout
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43       oflag=FLAGS
44              write as per the comma separated symbol list
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46       seek=N (or oseek=N) skip N obs-sized output blocks
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48       skip=N (or iseek=N) skip N ibs-sized input blocks
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50       status=LEVEL
51              The LEVEL of information to print to stderr;  'none'  suppresses
52              everything  but  error  messages,  'noxfer' suppresses the final
53              transfer statistics, 'progress' shows periodic transfer  statis‐
54              tics
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56       N  and  BYTES may be followed by the following multiplicative suffixes:
57       c=1, w=2, b=512,  kB=1000,  K=1024,  MB=1000*1000,  M=1024*1024,  xM=M,
58       GB=1000*1000*1000,  G=1024*1024*1024, and so on for T, P, E, Z, Y.  Bi‐
59       nary prefixes can be used, too: KiB=K, MiB=M, and so on.  If N ends  in
60       'B', it counts bytes not blocks.
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62       Each CONV symbol may be:
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64       ascii  from EBCDIC to ASCII
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66       ebcdic from ASCII to EBCDIC
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68       ibm    from ASCII to alternate EBCDIC
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70       block  pad newline-terminated records with spaces to cbs-size
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72       unblock
73              replace trailing spaces in cbs-size records with newline
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75       lcase  change upper case to lower case
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77       ucase  change lower case to upper case
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79       sparse try to seek rather than write all-NUL output blocks
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81       swab   swap every pair of input bytes
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83       sync   pad  every  input  block  with  NULs to ibs-size; when used with
84              block or unblock, pad with spaces rather than NULs
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86       excl   fail if the output file already exists
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88       nocreat
89              do not create the output file
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91       notrunc
92              do not truncate the output file
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94       noerror
95              continue after read errors
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97       fdatasync
98              physically write output file data before finishing
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100       fsync  likewise, but also write metadata
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102       Each FLAG symbol may be:
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104       append append mode (makes sense  only  for  output;  conv=notrunc  sug‐
105              gested)
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107       direct use direct I/O for data
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109       directory
110              fail unless a directory
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112       dsync  use synchronized I/O for data
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114       sync   likewise, but also for metadata
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116       fullblock
117              accumulate full blocks of input (iflag only)
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119       nonblock
120              use non-blocking I/O
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122       noatime
123              do not update access time
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125       nocache
126              Request to drop cache.  See also oflag=sync
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128       noctty do not assign controlling terminal from file
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130       nofollow
131              do not follow symlinks
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133       Sending a USR1 signal to a running 'dd' process makes it print I/O sta‐
134       tistics to standard error and then resume copying.
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136       Options are:
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138       --help display this help and exit
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140       --version
141              output version information and exit
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AUTHOR

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

147       GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
148       Report any translation bugs to <https://translationproject.org/team/>
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COPYRIGHT

151       Copyright © 2022 Free Software Foundation, Inc.   License  GPLv3+:  GNU
152       GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
153       This  is  free  software:  you  are free to change and redistribute it.
154       There is NO WARRANTY, to the extent permitted by law.
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SEE ALSO

157       Full documentation <https://www.gnu.org/software/coreutils/dd>
158       or available locally via: info '(coreutils) dd invocation'
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162GNU coreutils 9.1                  May 2023                              DD(1)