DD

Section: User Commands (1)
Updated: October 2004
 

NAME

dd - convert and copy a file  

SYNOPSIS

dd [OPTION]...  

DESCRIPTION

Copy a file, converting and formatting according to the options.

bs=BYTES
force ibs=BYTES and obs=BYTES
cbs=BYTES
convert BYTES bytes at a time
conv=KEYWORDS
convert the file as per the comma separated keyword list
count=BLOCKS
copy only BLOCKS input blocks
ibs=BYTES
read BYTES bytes at a time
if=FILE
read from FILE instead of stdin
obs=BYTES
write BYTES bytes at a time
of=FILE
write to FILE instead of stdout
seek=BLOCKS
skip BLOCKS obs-sized blocks at start of output
skip=BLOCKS
skip BLOCKS ibs-sized blocks at start of input
--help
display this help and exit
--version
output version information and exit

BLOCKS and BYTES may be followed by the following multiplicative suffixes: xM M, c 1, w 2, b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024, GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y. Each KEYWORD may be:

ascii
from EBCDIC to ASCII
ebcdic
from ASCII to EBCDIC
ibm
from ASCII to alternated 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
notrunc
do not truncate the output file
ucase
change lower case to upper case
swab
swap every pair of input bytes
noerror
continue after read errors
sync
pad every input block with NULs to ibs-size; when used
with block or unblock, pad with spaces rather than NULs

Note that sending a SIGUSR1 signal to a running `dd' process makes it print to standard error the number of records read and written so far, then to resume copying.

$ dd if=/dev/zero of=/dev/null& pid=$!
$ kill -USR1 $pid; sleep 1; kill $pid
10899206+0 records in 10899206+0 records out
 

AUTHOR

Written by Paul Rubin, David MacKenzie, and Stuart Kemp.  

REPORTING BUGS

Report bugs to <bug-coreutils@gnu.org>.  

COPYRIGHT

Copyright © 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

SEE ALSO

The full documentation for dd is maintained as a Texinfo manual. If the info and dd programs are properly installed at your site, the command
info coreutils dd

should give you access to the complete manual.


 

Index

NAME
SYNOPSIS
DESCRIPTION
AUTHOR
REPORTING BUGS
COPYRIGHT
SEE ALSO
blog comments powered by Disqus