lpr output filters

[Richard A. O'Keefe]

In article <9712 at cslb.CSL.SRI.COM> aida at csl.sri.com (Hitoshi Aida) writes:
>In article <16878 at mimsy.UUCP> chris at mimsy.UUCP (Chris Torek) writes:
>>The discussion is really about `files that can be viewed on a terminal
>>but not printed'.

>So, there is no perfect solution, but usually it is sufficient if making
>hard-copy is difficult enough.  How about this: as discussed early, make
>a special uid that can access the files.  Make a set-uid program which
>looks the termcap and display the content of the file in special manner.

How to crack the proposed solution:
(1) Write a terminal emulator that reads characters and escape sequences
    and builds screen images.
(2) Use 'script' to capture the bytes written by the program ('script'
    looks to the program like a tty).  Other operating systems have
    similar hooks, e.g. COMOUTPUT in PR1MOS, PHOTO in some DEC systems.
(3) Feed result of (2) into result of (1).

Seriously, if there is some information you want people to be able to
get at, but not to make off with, why not put it on microfiche and have
a 'fiche reader in the room?  If you think that would be too expensive,
then you don't care about keeping the data inside as you thought you did.
For better security than that, print one hard-copy, and put it in your
library as a desk copy.

Heck, what's to stop someone copying the stuff off the screen with a
camera, or even writing it down by hand?  At least providing the information
on 'fiche will make it look as though you are trying to _provide_ the
information...