Linux dd command usage

BKahler · Post by **BKahler** » Fri Apr 14, 2006 9:30 pm

Looking for general Linux help here.

We have a CD that was created in our Sony digital camera. The camera was writing to it just fine up until we finalized it and removed it from the camera. At that point there appears to have been a defect on the outer edge of the disc and the silvering is just gone.

We'd like to try and recover the files from this disk and someone mentioned to me that the linux dd command might work. However, not knowing enough about linux I'm leary of using a command that can mess things up if used wrong.

What would the command string be for me to try and read the files from the CD?

Anyone?!!

Thanks,

Brad

Post by **zoneminder** » Mon Apr 17, 2006 7:28 pm

The dd command is useful for bytewise copies of filesystems but I don't know how it would be used to recover a CD. I guess you could make a duplicate filesystem on a hrad disk and play with that one (so not messing up your cd).

The basic syntax would be something like

Code: Select all

dd if=/dev/cdrom of=/dev/hdc1

to copy a cdrom to a partition on a hard disk. However there are a lot of options so you really need to 'man' dd first. The main danger is not to your cd but that you might crap on your hard disk filesystems.

Phil

bosskong · Post by **bosskong** » Mon Apr 17, 2006 7:37 pm

I think you could do the following:
"dd if=/dev/hdc of=$HOME/cdbackup.raw"
where /dev/hdc is the name of your cd reader device and $HOME/cdbackup.raw is the path and name of the file where you would like to store the information.

The dd command simply does a raw copy of each block on the device. With the above command, you're simply copying each block on device /dev/hdc into a single file called cdbackup.raw in your home directory. It may help you to make a backup copy of the raw data in the pictures, but they're not going to be split up into individual files, so I don't know if it would help you.