Clarification needed about prebuilts and CD

[trncyng]

Following the Gentoo Linux x86 Handbook, Ch.11 Finalizing Your Gentoo Installation, under "Optional: Install GRP Packages," it tells us to
export PKGDIR="/mnt/cdrom"
to install packages we want from the CD (which I presume is to emerge <packagename>)

My questions is, is this a temporary convenient method when we want to install prebuilts from the Packages CD using simple emerge?

Do I have to undo this export if I want to use prebuilts that are on the hard disk and not CD? Or is this unset when I do an emerge sync?

I ask this because in the same Handbook, under Working With Gentoo > Portage and Software, it says that Portage looks in /usr/portage/packages/All for precompiled packages to see if the necessary files are already available (if not it goes to the Internet). If this is the case, can I simply copy the package(s) I want from the Packages CD into /usr/portage/packages/All and so have no need to issue the above export?

Thanks for any advice

[furkan]

1) yes for example you want install just an little package and with that you don't need to copy the files from packages cd to hardware....
2) you have just

[trncyng]

Thanks, it does. The Handbook is very well written. Just once in a rare while, I cannot tell the difference between general concepts and a specific practical application. Gentoo is way ahead of the rest of the others in documentation!