Add command for overwriting harddisks

pages/04.other/16.useful-commands/default.en.md

@@ -18,3 +18,11 @@ Using find with its `exec` switch one can set different permissions based on the
 One example would be only changing file or directory permissions.  
 `$ find (directory) -type f -exec chmod 744 {} +`  
 Replacing `-type f` with `-type d` would execute the `chmod` for directories instead.  
+
+## Various
+### Overwrite disk with pseudorandom data
+Using openssl on CPUs with AES acceleration one can create pseudorandom data with high speeds.  
+Much faster than `/dev/urandom` at least  
+`# openssl enc -aes-128-ctr -md sha512 -pbkdf2 -nosalt -pass file:/dev/urandom < /dev/zero | pv > (target disk)`  
+Around 2GiB/s on my Ryzen 7 1700x if output to `/dev/null`  
+