OT: How to find amount of free memory from within a C program

[Ranjan Maitra]

Dear friends,

This is a general question with the exception that I use Fedora
exclusively:-) Besides, this -- along with R-help -- are the two most
knowledgeable and helpful mailing lists I know of.

In any case, is there a ready way (function or such) to find out how
much memory is available to me from inside a C program? I would like
this to be as generic as possible.

I tried getrusage() but I could not figure out if there was a field for
free/available memory in the rusage struct. In fact, there does not
seem to be. 

Any other suggestions?

Many thanks again for this OT help, and best wishes,
Ranjan