i/o filtering with C

[Morgan Schweers]

Greetings,
    Here's a question which probably should be immortalized in the FAQ, but
since I'm new to this group I'll throw it out here anyway.
 
    I'm looking to filter all i/o for an interactive process.  For example,
if the character sequence ~!@ appears, my program would change it to something
else.  If a certain sequence is typed, the filter would change it to something
else.  All this has to be interactive, and allow full system mobility.
 
    It's under unix, and under C.  (I don't know how to cross-post, else I
would have.)
 
    I got this murderous warning when I began posting this message up about
money spent on this message.  (I'm still glancing over my shoulder for the
net.police to come and tell me this message is useless and costing too many
people too much money...)  With this in mind, I suppose all responses should
be in e-mail.  To quote many messages, "I'll summarize in a post if I get
enough information."
 
                                                         --  Morgan
 P.S.  Can anyone give me an estimate of how much a single message actually
     costs?
 P.P.S.  Is this disclaimer I'm about to add really *THAT* important?
 
+--------------------------------------------------------------------------+
| Morgan Schweers             Internet: ms at wheaties.ai.mit.edu             |
+--------------------------------------------------------------------------+
|     Any opinions entered in this message are not the opinions of anyone  |
| I know.  Heck, they may not even be MY opinions.                         |
+--------------------------------------------------------------------------+