Is there a way to make a permanent pseudo-file, whose contents may dynamically change? I'm thinking of something like an SQL view here. I've been trying to do this with pipes, but I haven't been able to crack it.

For example, I have two files, “half1” and “half2”, which are subject to change at any time. I need a permanent file, “whole”, that always contains the concatenation of the current “half1” and “half2” files. And “whole” must appear to be a file (I can't just pipe it in on a command line) for this particular application.

I can obviously do a one-time concatenation (cat half1 half2 > whole) but subsequent changes in “half1” or “half2” won't be reflected in “whole”. Is there some way to make this live/dynamic?

I'm on SunOS 5.10