[wolfgang42]

> there is nothing preventing the development of software to overwrite data before unlink(2) is called.

It’s not that simple: this command already exists, it’s called `shred`, and as the manual[1] notes:

The shred command relies on a crucial assumption: that the file system and hardware overwrite data in place. Although this is common and is the traditional way to do things, many modern file system designs do not satisfy this assumption.

[1] https://www.gnu.org/software/coreutils/manual/html_node/shre...