cmd:dd

Prev		Next

*Tags*: backup boot partition, bootsector

Usage

save MBR

dd if=/dev/hda of=/export/sysbaks/hda-img.mbr bs=512 count=1
dd if=/dev/hdb of=/export/sysbaks/hdb-img.mbr bs=512 count=1

save C: boot

dd if=/dev/hda3 of=/export/sysbaks/hda-img.btc bs=512 count=1
dd if=/dev/hdb3 of=/export/sysbaks/hdb-img.btc bs=512 count=1

create a big file

dd if=/dev/zero of=bigf bs=1024 count=

Comments on creating big file

/dev/null is no good

$ dd if=/dev/null of=bigf count=69200 bs=1024
0+0 records in
0+0 records out
0 bytes transferred in 0.000385 seconds (0 bytes/sec)

$ lgg bigf
-rw-rw----  1 0 08-03 23:02 bigf

seek is no good

$ dd of=bigf bs=1024 count=0 seek=$((70860516/1024)+1)

$ lgg bigf
-rw-rw----  1 70860800 08-03 22:44 bigf

$ du -kL bigf
4       bigf

Help

you can use lilo.conf specifying the boot partition or you can simply use dd to work with bootsectors. for example, to make a backup copy of a bootsector in a partition, say, hda1, you could do:

dd if=/dev/hda1 of=bootsect.hda1 bs=512 count=1

if you want to recover later you do:

dd if=bootsect.hda1 of=/dev/hda1 bs=512 coount=1

in the same way you could copy hda1 bootsector to hda2 bootsector:

dd if=/dev/hda1 of=/dev/hda2 bs=512 count=1

Patrick Machado