1 .\" DO NOT MODIFY THIS FILE! It was generated by help2man 1.35.
2 .TH DD "1" "March 2007" "GNU coreutils 6.9" "User Commands"
4 dd \- convert and copy a file
12 .\" Add any additional description here
14 Copy a file, converting and formatting according to the operands.
17 force ibs=BYTES and obs=BYTES
20 convert BYTES bytes at a time
23 convert the file as per the comma separated symbol list
26 copy only BLOCKS input blocks
29 read BYTES bytes at a time
32 read from FILE instead of stdin
35 read as per the comma separated symbol list
38 write BYTES bytes at a time
41 write to FILE instead of stdout
44 write as per the comma separated symbol list
47 skip BLOCKS obs\-sized blocks at start of output
50 skip BLOCKS ibs\-sized blocks at start of input
53 suppress transfer statistics
55 BLOCKS and BYTES may be followed by the following multiplicative suffixes:
56 xM M, c 1, w 2, b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
57 GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.
59 Each CONV symbol may be:
68 from ASCII to alternate EBCDIC
71 pad newline\-terminated records with spaces to cbs\-size
74 replace trailing spaces in cbs\-size records with newline
77 change upper case to lower case
80 do not create the output file
83 fail if the output file already exists
86 do not truncate the output file
89 change lower case to upper case
92 swap every pair of input bytes
95 continue after read errors
98 pad every input block with NULs to ibs\-size; when used
99 with block or unblock, pad with spaces rather than NULs
102 physically write output file data before finishing
105 likewise, but also write metadata
107 Each FLAG symbol may be:
110 append mode (makes sense only for output; conv=notrunc suggested)
113 use direct I/O for data
115 directory fail unless a directory
116 dsync use synchronized I/O for data
117 sync likewise, but also for metadata
118 nonblock use non\-blocking I/O
119 noatime do not update access time
120 noctty do not assign controlling terminal from file
121 nofollow do not follow symlinks
123 Sending a USR1 signal to a running `dd' process makes it
124 print I/O statistics to standard error and then resume copying.
126 \f(CW$ dd if=/dev/zero of=/dev/null& pid=$!\fR
128 \f(CW$ kill -USR1 $pid; sleep 1; kill $pid\fR
130 18335302+0 records in
131 18335302+0 records out
132 9387674624 bytes (9.4 GB) copied, 34.6279 seconds, 271 MB/s
137 display this help and exit
140 output version information and exit
142 Written by Paul Rubin, David MacKenzie, and Stuart Kemp.
144 Report bugs to <bug\-coreutils@gnu.org>.
146 Copyright \(co 2007 Free Software Foundation, Inc.
148 This is free software. You may redistribute copies of it under the terms of
149 the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
150 There is NO WARRANTY, to the extent permitted by law.
152 The full documentation for
154 is maintained as a Texinfo manual. If the
158 programs are properly installed at your site, the command
162 should give you access to the complete manual.