C-shell programming

[Reiner Wilhelms]

I'd like to create a c shell program which reads from 3 files and
generates 1 (or more ) output file(s). 
Calling this csh script will look like this:

	% my_shell_script input1 input2 input3  output

The trouble is, I only know how to read from one file, using the input
redirection. I want to read from within that shell script instead of
forking a new process, or writing a C-program.

Can this be done??

I am working on a sun workstation, SunOS 4.0.3c

Thanks in advance.

Reiner