rm only removes OS "metadata" -- it removes the link to the reference. The file's data is not touched. Here's a stupid but effective way I came up with to del

rm only removes OS "metadata" -- it removes the link to the reference. The file's data is not touched. Here's a stupid but effective way I came up with to delete the data in files when they are too large to be stored in RAM: Use dd on the device where the file is stored. Files intended for eventual deletion can be stored on their own dedicated virtual block devices, or "file-backed virtual disks". Unless things have changed, on OpenBSD these virtual block devices can be created from /dev/vnd. To create a location to store the file(s) at, create an empty "backing" file with dd, associate it with a vnd, newfs the vnd and mount it. To delete all the files on the mounted vnd, either umount and dd if=/dev/zero of=/dev/vnd{no}d or dd if=/dev/zero of=rvnd{no}d and umount. One can also configure a cryptographic disk device over the vnd using a random throwaway password.