dd (1) - Linux Man Pages
dd: convert and copy a file
NAMEdd - convert and copy a file
Copy a file, converting and formatting according to the operands.
- read and write up to BYTES bytes at a time
- convert BYTES bytes at a time
- convert the file as per the comma separated symbol list
- copy only N input blocks
- read up to BYTES bytes at a time (default: 512)
- read from FILE instead of stdin
- read as per the comma separated symbol list
- write BYTES bytes at a time (default: 512)
- write to FILE instead of stdout
- write as per the comma separated symbol list
- skip N obs-sized blocks at start of output
- skip N ibs-sized blocks at start of input
- The LEVEL of information to print to stderr; 'none' suppresses everything but error messages, 'noxfer' suppresses the final transfer statistics, 'progress' shows periodic transfer statistics
N and BYTES may be followed by the following multiplicative suffixes: c =1, w =2, b =512, kB =1000, K =1024, MB =1000*1000, M =1024*1024, xM =M GB =1000*1000*1000, G =1024*1024*1024, and so on for T, P, E, Z, Y.
Each CONV symbol may be:
- from EBCDIC to ASCII
- from ASCII to EBCDIC
- from ASCII to alternate EBCDIC
- pad newline-terminated records with spaces to cbs-size
- replace trailing spaces in cbs-size records with newline
- change upper case to lower case
- change lower case to upper case
- try to seek rather than write the output for NUL input blocks
- swap every pair of input bytes
- pad every input block with NULs to ibs-size; when used with block or unblock, pad with spaces rather than NULs
- fail if the output file already exists
- do not create the output file
- do not truncate the output file
- continue after read errors
- physically write output file data before finishing
- likewise, but also write metadata
Each FLAG symbol may be:
- append mode (makes sense only for output; conv=notrunc suggested)
- use direct I/O for data
- fail unless a directory
- use synchronized I/O for data
- likewise, but also for metadata
- accumulate full blocks of input (iflag only)
- use non-blocking I/O
- do not update access time
- discard cached data
- do not assign controlling terminal from file
- do not follow symlinks
- treat 'count=N' as a byte count (iflag only)
- treat 'skip=N' as a byte count (iflag only)
- treat 'seek=N' as a byte count (oflag only)
Sending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard error and then resume copying.
$ dd if=/dev/zero of=/dev/null& pid=$!
$ kill -USR1 $pid; sleep 1; kill $pid
- 18335302+0 records in 18335302+0 records out 9387674624 bytes (9.4 GB) copied, 34.6279 seconds, 271 MB/s
- display this help and exit
- output version information and exit
AUTHORWritten by Paul Rubin, David MacKenzie, and Stuart Kemp.
COPYRIGHTCopyright © 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSOThe 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 invocation'
should give you access to the complete manual.
Linux man pages generated by: SysTutorials