# dd if=/dev/zero of=/dev/sdX bs=4096

# dd if=/dev/urandom of=/dev/sdX bs=4096

$ wipe -r -q /path/to/wipe

shred

shred (from the coreutils package) is a Unix command that can be used to securely delete individual files or full devices so that they can be recovered only with great difficulty with specialised hardware, if at all. By default shred uses three passes, writing pseudo-random data to the device during each pass. This can be reduced or increased.

The following command invokes shred with its default settings and displays the progress.

# shred -v /dev/sdX

Alternatively, shred can be instructed to do only one pass, with entropy from e.g. /dev/urandom.

# shred --verbose --random-source=/dev/urandom -n1 /dev/sdX