lpr output filters

[Hitoshi Aida]

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'.
>
>It is worth noting that this effort is doomed to failure, as there
>are terminals that are printers, or have integral printers.
>
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.
For example, use cursor motion to write characters in random order,
produce different style of output (e.g. different number of columns in
multi-column output) on each page to make the collection of "screen dump"
difficult, and so on.  Of course it should refuse to show the file if the
terminal looks like a printer (i.e. lacks some basic terminal capabilities).
--------
Hitoshi AIDA (aida at csl.sri.com)
Computer Science Laboratory, SRI International