DD(1)

NAME
dd - convert a file while copying it

SYNOPSIS
dd [--help] [--version] [if=file] [of=file] [ibs=bytes] [obs=bytes] [bs=bytes] [cbs=bytes] [skip=blocks] [seek=blocks] [count=blocks] [conv={ascii,ebcdic,ibm,block,unblock,lcase,ucase,swab,noerror,notrunc, sync}]

DESCRIPTION
This documentation is no longer being maintained and may be inaccurate or incomplete. The Texinfo documentation is now the authoritative source.

This manual page documents the GNU version of dd. dd copies a file (from the standard input to the standard output, by default) with a user-selectable blocksize, while optionally performing conversions on it.

  OPTIONS
Numbers can be followed by a multiplier:
b=512, c=1, k=1024, w=2, xm=number m

--help
    Print a usage message on standard output and exit successfully.

--version
    Print version information on standard output then exit successfully.

if=file
    Read from file instead of the standard input.

of=file
    Write to file instead of the standard output. Unless conv=notrunc is given, truncate file to the size specified by seek= (0 bytes if seek= is not given).

ibs=bytes
    Read bytes bytes at a time.

obs=bytes
    Write bytes bytes at a time.

bs=bytes
    Read and write bytes bytes at atime. Override ibs and obs.

cbs=bytes
    Convert bytes bytes at a time.

skip=blocks
    Skip blocks ibs-sized blocks at start of input.

seek=blocks
    Skip blocks obs-sized blocks at start of output.

count=blocks
    Copy only blocks ibs-sized input blocks.

conv=conversion[,conversion...]
    Convert the file as specified by the conversion arguments.
    Conversions:

    ascii
        Convert EBCDIC to ASCII.

    ebcdic
        Convert ASCII to EBCDIC.

    ibm Convert ASCII to alternate EBCDIC.

    block
        Pad newline-terminated records to size of cbs, replacing newline with trailing spaces.

    unblock
        Replace trailing spaces in cbs-sized block with newline.

    lcase
        Change uppercase characters to lowercase.

    ucase
        Change lowercase characters to uppercase.

    swab
        Swap every pair of input bytes. Unlike the Unix dd, this works when an odd number of bytes are read. If the input file contains an odd number of bytes, 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 NULs.