# dd

## NAME



           dd - convert and copy a file
    


## SYNOPSIS



           **dd**[_OPERAND_]...
           **dd** _OPTION_
    


## DESCRIPTION



           Copy a file, converting and formatting according to the operands.
    
           bs=BYTES
                  read and write up to BYTES bytes at a time (default: 512);
                  overrides ibs and obs
    
           cbs=BYTES
                  convert BYTES bytes at a time
    
           conv=CONVS
                  convert the file as per the comma separated symbol list
    
           count=N
                  copy only N input blocks
    
           ibs=BYTES
                  read up to BYTES bytes at a time (default: 512)
    
           if=FILE
                  read from FILE instead of stdin
    
           iflag=FLAGS
                  read as per the comma separated symbol list
    
           obs=BYTES
                  write BYTES bytes at a time (default: 512)
    
           of=FILE
                  write to FILE instead of stdout
    
           oflag=FLAGS
                  write as per the comma separated symbol list
    
           seek=N (or oseek=N) skip N obs-sized output blocks
    
           skip=N (or iseek=N) skip N ibs-sized input blocks
    
           status=LEVEL
                  The LEVEL of information to print to stderr; 'none'
                  suppresses everything but error messages, 'noxfer'
                  suppresses the final transfer statistics, 'progress' shows
                  periodic transfer statistics
    
           N and BYTES may be followed by the following multiplicative
           suffixes: c=1, w=2, b=512, kB=1000, K=1024, MB=1000*1000,
           M=1024*1024, xM=M, GB=1000*1000*1000, G=1024*1024*1024, and so on
           for T, P, E, Z, Y, R, Q.  Binary prefixes can be used, too: KiB=K,
           MiB=M, and so on.  If N ends in 'B', it counts bytes not blocks.
    
           Each CONV symbol may be:
    
           ascii  from EBCDIC to ASCII
    
           ebcdic from ASCII to EBCDIC
    
           ibm    from ASCII to alternate EBCDIC
    
           block  pad newline-terminated records with spaces to cbs-size
    
           unblock
                  replace trailing spaces in cbs-size records with newline
    
           lcase  change upper case to lower case
    
           ucase  change lower case to upper case
    
           sparse try to seek rather than write all-NUL output blocks
    
           swab   swap every pair of input bytes
    
           sync   pad every input block with NULs to ibs-size; when used with
                  block or unblock, pad with spaces rather than NULs
    
           excl   fail if the output file already exists
    
           nocreat
                  do not create the output file
    
           notrunc
                  do not truncate the output file
    
           noerror
                  continue after read errors
    
           fdatasync
                  physically write output file data before finishing
    
           fsync  likewise, but also write metadata
    
           Each FLAG symbol may be:
    
           append append mode (makes sense only for output; conv=notrunc
                  suggested)
    
           direct use direct I/O for data
    
           directory
                  fail unless a directory
    
           dsync  use synchronized I/O for data
    
           sync   likewise, but also for metadata
    
           fullblock
                  accumulate full blocks of input (iflag only)
    
           nonblock
                  use non-blocking I/O
    
           noatime
                  do not update access time
    
           nocache
                  Request to drop cache.  See also oflag=sync
    
           noctty do not assign controlling terminal from file
    
           nofollow
                  do not follow symlinks
    
           Sending a USR1 signal to a running 'dd' process makes it print I/O
           statistics to standard error and then resume copying.
    
           Options are:
    
           **--help** display this help and exit
    
           **--version**
                  output version information and exit
    


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