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(fileutils.info)dd invocation

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`dd': Convert and copy a file
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   `dd' copies a file (from standard input to standard output, by
default) with a changeable I/O block size, while optionally performing
conversions on it.  Synopsis:

     dd [OPTION]...

   The program accepts the following options.  Also see Note: Common
options.

   The numeric-valued options below (BYTES and BLOCKS) can be followed
by a multiplier: `b'=512, `c'=1, `w'=2, `xM'=M, or any of the standard
block size suffixes like `k'=1024 (Note: Block size).

   Use different `dd' invocations to use different block sizes for
skipping and I/O.  For example, the following shell commands copy data
in 512 kB blocks between a disk and a tape, but do not save or restore a
4 kB label at the start of the disk:

     disk=/dev/rdsk/c0t1d0s2
     tape=/dev/rmt/0
     
     # Copy all but the label from disk to tape.
     (dd bs=4k skip=1 count=0 && dd bs=512k) <$disk >$tape
     
     # Copy from tape back to disk, but leave the disk label alone.
     (dd bs=4k seek=1 count=0 && dd bs=512k) <$tape >$disk

`if=FILE'
     Read from FILE instead of standard input.

`of=FILE'
     Write to FILE instead of standard output.  Unless `conv=notrunc'
     is given, `dd' truncates FILE to zero bytes (or the size specified
     with `seek=').

`ibs=BYTES'
     Read BYTES bytes at a time.

`obs=BYTES'
     Write BYTES bytes at a time.

`bs=BYTES'
     Both read and write BYTES bytes at a time.  This overrides `ibs'
     and `obs'.

`cbs=BYTES'
     Convert BYTES bytes at a time.

`skip=BLOCKS'
     Skip BLOCKS `ibs'-byte blocks in the input file before copying.

`seek=BLOCKS'
     Skip BLOCKS `obs'-byte blocks in the output file before copying.

`count=BLOCKS'
     Copy BLOCKS `ibs'-byte blocks from the input file, instead of
     everything until the end of the file.

`conv=CONVERSION[,CONVERSION]...'
     Convert the file as specified by the CONVERSION argument(s).  (No
     spaces around any comma(s).)

     Conversions:

    `ascii'
          Convert EBCDIC to ASCII.

    `ebcdic'
          Convert ASCII to EBCDIC.

    `ibm'
          Convert ASCII to alternate EBCDIC.

    `block'
          For each line in the input, output `cbs' bytes, replacing the
          input newline with a space and padding with spaces as
          necessary.

    `unblock'
          Replace trailing spaces in each `cbs'-sized input block with a
          newline.

    `lcase'
          Change uppercase letters to lowercase.

    `ucase'
          Change lowercase letters to uppercase.

    `swab'
          Swap every pair of input bytes.  GNU `dd', unlike others,
          works when an odd number of bytes are read--the last byte is
          simply copied (since there is nothing to swap it with).

    `noerror'
          Continue after read errors.

    `notrunc'
          Do not truncate the output file.

    `sync'
          Pad every input block to size of `ibs' with trailing zero
          bytes.  When use with `block' or `unblock', pad with spaces
          instead of zero bytes.