Using environment variables without leaking memory?

[Paul Brook]

> How do I set (and reset) environment variables without leaking memory?  I
> _think_ if I use setenv() instead of putenv() it won't leak memory (freeing
> the old one), but if I previously used putenv() and then call setenv() to
> update that variable, does it free the old chunk of memory?  Or not?  (How
> does it know?  Presumably the environment variables inherited from a parent
> process weren't allocated with malloc()...)

When you create a new process the kernel makes a new copy of the environment. 
Usually this is put at the top of the new process' stack. The environment is 
not shared between multiple processes.

Paul