How to wipeout your hard disk perfectly in Ubuntu

Here is a command shread which can be used to in bash terminal of Ubuntu to wipeout your harddisk completely without leaving any chances for further recovery. Please dont try it unless otherwise you dont have no other use with your current system...

$ shread -v -n 1 -z /dev/hda

Options

-f, --force
       change permissions to allow writing if necessary

       -n, --iterations=N
       Overwrite N times instead of the default (25)

       -s, --size=N
       shred this many bytes (suffixes like K, M, G accepted)

       -u, --remove
       truncate and remove file after overwriting

       -v, --verbose
       show progress

       -x, --exact
       do not round file sizes up to the next full block;

       this is the default for non-regular files

       -z, --zero
       add a final overwrite with zeros to hide shredding