dd

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It can strip headers, extract parts of binary files and write into the middle of floppy disks; it is used by the Linux kernel Makefiles to make boot images.
Example 3

Sometimes data arrives from sources in unusual formats. For example, every time I read a tape made on an SGI machine, the bytes are swapped. The dd command takes this in stride, swapping the bytes as required. The ability to use dd in a pipe with rsh means that the tape device on any *nix system is accessible, given the proper rlogin setup.

Example 3: Byte Swapping with Remote Access of Magnet Tape:rsh sgi.with.tape dd bs=256b if=/dev/rmt0 conv=swab | tar xvf -

The dd runs on the SGI and swaps the bytes before writing to the tar command running on the local host.

Example 4

Murphy's Law was postulated long before digital computers, but it seems it was specifically targeted for them. When you need to read a floppy or tape, it is the only copy in the universe and you have a deadline past due, that is when you will have a bad spot on the magnetic media, and your data will be unreadable. To the rescue comes dd, which can read all the good data around the bad spot and continue after the error is encountered. Sometimes this is all that is needed to recover the important data.

Example 4: Error Handlingi:dd bs=265b conv=noerror if=/dev/st0 of=/tmp/bad.tape.image

Example 5

The Linux kernel Makefiles use dd to build the boot image. In the Alpha Makefile /usr/src/linux/arch/alpha/boot/Makefile, the srmboot target issues the command:

Example 5. Kernel Image Makefile:dd if=bootimage of=$(BOOTDEV) bs=512 seek=1 skip=1

This skips the first 512 bytes of the input bootimage file (skip=1) and writes starting at the second sector of the $(BOOTDEV) device (seek=1). A typical use of dd is to skip executable headers and begin writing in the middle of a device, skipping volume and partition data. As this can cause your disk to lose file system data, please test and use these applications with care.

Credits

The dd command has been around since the 1970s, ported to many systems, rewritten many times, and tested by time as a useful tool. The current Linux version is GNU dd GNU fileutils 3.12, written by Paul Rubin, David MacKenzie, and Stuart Kemp, Copyright © 1985, 1990, 1991 Free Software Foundation, Inc.

GNU dd is found in the fileutils collection, with the current version at the URL ftp://prep.ai.mit.edu/pub/gnu/fileutils-3.12.tar.gz or a mirror near you.

Other major versions include SYSV and BSD, with the BSD source version 5.16 4/28/93 derived from software contributed to Berkeley by Keith Muller of the University of California, San Diego and Lance Visser of Convex Computer Corporation, Copyright © 1991 The Regents of the University of California.

Sam Chessman (SSC3) (chessman@wauug.erols.com)

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About dd command

Cathrine gabler's picture

dd is a common unix progarmme used for copying and conversation of raw data. It is an application used for convert and copy a file according to the referred manual page. DD stands for data description.
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Lara

komik yazılar's picture

To burn the data on a disc, pipe it into cdrecord (http://linux.die.net/man/1/cdrecord)

To burn the image

Anonymous's picture

To burn the data on a disc, pipe it into cdrecord (http://linux.die.net/man/1/cdrecord)

See all usefull dd command

Anonymous's picture

See all usefull dd command

Previously undocumented uses of dd

AwesomeMachine's picture

dd to burn iso file

dabash's picture

how can we use dd command to burn iso file

thanks in advance

Re: Take Command: dd

Anonymous's picture

Many thanks for the excellent info Sam

Maan A Hatab

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