Any regex wizard reading this?

If so, what is the C POSIX regex (you know regcomp & friends) equivalent of this python regular expresion:

re.compile(r'^([a-z][a-z0-9_\-\.]*)=', re.IGNORECASE)

Because it sure isn't this:

regcomp(&re,"^([a-z][a-z0-9_\-\.]*)=",REG_ICASE)

I have been playing with it for two hours and am bored :-)