- About dd : To convert and copy the olds
- It comes from “coreutils-8.4-9.el6.i686” package.
- Path: /bin/dd
Examples:
1. To copy a file
| $ dd if=old.txt of=old.txt |
2. To read and write specified bytes of a file at a time
| $ dd bs=1024 if=old.txt of=old.txt |
3. To convert a file to a specified format
| $ dd bs=1024 if=old.txt of=new.txt conv=ascii (from EBCDIC to ASCII) $ dd bs=1024 if=old.txt of=new.txt conv=ebcdic (from ASCII to EBCDIC) $ dd bs=1024 if=old.txt of=new.txt conv=ibm (from ASCII to alternate EBCDIC) $ dd bs=1024 if=old.txt of=new.txt conv=block (pad oldline-terminated records with spaces to cbs-size) $ dd bs=1024 if=old.txt of=new.txt conv=unblock (replace trailing spaces in cbs-size records with oldline) $ dd bs=1024 if=old.txt of=new.txt conv=lcase (change upper case to lower case) $ dd bs=1024 if=old.txt of=new.txt conv=excl (fail if the output old already exists) $ dd bs=1024 if=old.txt of=new.txt conv=notrunc (do not truncate the output old) $ dd bs=1024 if=old.txt of=new.txt conv=ucase (change lower case to upper case) $ dd bs=1024 if=old.txt of=new.txt conv=swab (swap every pair of input bytes) $ dd bs=1024 if=old.txt of=new.txt conv=noerror (continue after read errors) $ dd bs=1024 if=old.txt of=new.txt conv=sync (pad every input block with NULs to ibs-size) $ dd bs=1024 if=old.txt of=new.txt conv=fdatasync (physically write output old data before finishing) $ dd bs=1024 if=old.txt of=new.txt conv=fsync (likewise, but also write metadata) |
4. To copy only specified number of blocks
| $ dd count=1024 if=old.txt of=new.txt |
5. To copy a file with specifying a flag
| $ dd if=old.txt of=new.txt oflag=append $ dd if=old.txt iflag=directory of=new.txt oflag=directory $ dd if=old.txt iflag=noatime of=new.txt oflag=append |
6. To convert specified bytes at a time
| $ dd cbs=1024 if=old.txt of=new.txt |
7. To read specified number of bytes at a time
| $ dd ibs=1024 if=old.txt of=new.txt |
8. To write specified number of bytes at a time
| $ dd obs=1024 if=old.txt of=new.txt |
9. To skip specified number of blocks at start of o/p
| $ dd seek=1024 if=old.txt of=new.txt |
10. To skip specified number of blocks at start of i/p
| $ dd skip=1024 if=old.txt of=new.txt |
11. To suppress the transfer statistics
| $ dd status=noxfer if=old.txt of=new.txt |
Cocktail Examples
12. To erase the partition table for a device
| $ dd if=/dev/zero of=/dev/sda4 bs=512 count=1 |
