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.TH DD 1 "GNU File Utilities" "FSF" \" -*- nroff -*-
.SH NAME
dd \- convert a file while copying it
.SH SYNOPSIS
.B 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}]
.SH DESCRIPTION
This documentation is no longer being maintained and may be inaccurate
or incomplete. The Texinfo documentation is now the authoritative source.
.PP
This manual page
documents the GNU version of
.BR dd .
.B 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.
.SS OPTIONS
Numbers can be followed by a multiplier:
.br
b=512, c=1, k=1024, w=2, xm=number m
.TP
.I "\-\-help"
Print a usage message on standard output and exit successfully.
.TP
.I "\-\-version"
Print version information on standard output then exit successfully.
.TP
.I if=file
Read from
.I file
instead of the standard input.
.TP
.I of=file
Write to
.I file
instead of the standard output.
Unless
.I conv=notrunc
is given, truncate
.I file
to the size specified by
.I seek=
(0 bytes if
.I seek=
is not given).
.TP
.I ibs=bytes
Read
.I bytes
bytes at a time.
.TP
.I obs=bytes
Write
.I bytes
bytes at a time.
.TP
.I bs=bytes
Read and write
.I bytes
bytes at atime. Override ibs and obs.
.TP
.I cbs=bytes
Convert
.I bytes
bytes at a time.
.TP
.I skip=blocks
Skip
.I blocks
ibs-sized blocks at start of input.
.TP
.I seek=blocks
Skip
.I blocks
obs-sized blocks at start of output.
.TP
.I count=blocks
Copy only
.I blocks
ibs-sized input blocks.
.TP
.I conv=conversion[,conversion...]
Convert the file as specified by the
.I conversion
arguments.
.RS
Conversions:
.TP
ascii
Convert EBCDIC to ASCII.
.TP
ebcdic
Convert ASCII to EBCDIC.
.TP
ibm
Convert ASCII to alternate EBCDIC.
.TP
block
Pad newline-terminated records to size of cbs, replacing newline with
trailing spaces.
.TP
unblock
Replace trailing spaces in cbs-sized block with newline.
.TP
lcase
Change uppercase characters to lowercase.
.TP
ucase
Change lowercase characters to uppercase.
.TP
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).
.TP
noerror
Continue after read errors.
.TP
notrunc
Do not truncate the output file.
.TP
sync
Pad every input block to size of ibs with trailing NULs.
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