I fairly innocuous question ;^). How does ghc-pkg know where are the *package.conf files are located?

#!/bin/sh

GHCPKGBIN=/usr/local/lib/ghc-6.8.2/ghc-pkg.bin

PKGCONF=/usr/local/lib/ghc-6.8.2/package.conf

exec $GHCPKGBIN --global-conf $PKGCONF ${1+"$@"}