[Nottingham] Secure deletion of files

[David Aldred]

A question arising from a discussion at work: how secure is deletion of files 
in Linux?  

Specifically, if I'm working on something for my employer using my own PC, and 
need it completely deleted and irrecoverable afterwards, can I do that?

And is there any way of doing it retrospectively, if I were to forget at the 
time and simply delete the file in the usual way?

(The video about security which triggered the discussion suggested a way of 
securely deleting your files under Windows, which would be better than 
nothing but still not particularly secure - and illustrated it with a video 
of someone working on a Mac!).

-- 
David Aldred