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 skip N obs-sized blocks at start of output
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48       skip=N skip N ibs-sized blocks at start of input
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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: c
57       =1, w =2, b =512, kB =1000, K =1024, MB =1000*1000,  M  =1024*1024,  xM
58       =M, GB =1000*1000*1000, G =1024*1024*1024, and so on for T, P, E, Z, Y.
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60       Each CONV symbol may be:
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62       ascii  from EBCDIC to ASCII
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64       ebcdic from ASCII to EBCDIC
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66       ibm    from ASCII to alternate EBCDIC
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68       block  pad newline-terminated records with spaces to cbs-size
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70       unblock
71              replace trailing spaces in cbs-size records with newline
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73       lcase  change upper case to lower case
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75       ucase  change lower case to upper case
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77       sparse try to seek rather than write the output for NUL input blocks
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79       swab   swap every pair of input bytes
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81       sync   pad  every  input  block  with  NULs to ibs-size; when used with
82              block or unblock, pad with spaces rather than NULs
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84       excl   fail if the output file already exists
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86       nocreat
87              do not create the output file
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89       notrunc
90              do not truncate the output file
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92       noerror
93              continue after read errors
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95       fdatasync
96              physically write output file data before finishing
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98       fsync  likewise, but also write metadata
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100       Each FLAG symbol may be:
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102       append append mode (makes sense  only  for  output;  conv=notrunc  sug‐
103              gested)
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105       direct use direct I/O for data
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107       directory
108              fail unless a directory
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110       dsync  use synchronized I/O for data
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112       sync   likewise, but also for metadata
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114       fullblock
115              accumulate full blocks of input (iflag only)
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117       nonblock
118              use non-blocking I/O
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120       noatime
121              do not update access time
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123       nocache
124              Request to drop cache.  See also oflag=sync
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126       noctty do not assign controlling terminal from file
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128       nofollow
129              do not follow symlinks
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131       count_bytes
132              treat 'count=N' as a byte count (iflag only)
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134       skip_bytes
135              treat 'skip=N' as a byte count (iflag only)
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137       seek_bytes
138              treat 'seek=N' as a byte count (oflag only)
139
140       Sending a USR1 signal to a running 'dd' process makes it print I/O sta‐
141       tistics to standard error and then resume copying.
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143       Options are:
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145       --help display this help and exit
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147       --version
148              output version information and exit
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AUTHOR

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

154       GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
155       Report dd translation bugs to <https://translationproject.org/team/>
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COPYRIGHT

158       Copyright © 2018 Free Software Foundation, Inc.   License  GPLv3+:  GNU
159       GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
160       This  is  free  software:  you  are free to change and redistribute it.
161       There is NO WARRANTY, to the extent permitted by law.
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SEE ALSO

164       Full documentation at: <https://www.gnu.org/software/coreutils/dd>
165       or available locally via: info '(coreutils) dd invocation'
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169GNU coreutils 8.30                 July 2018                             DD(1)