[gentoo-user] Emerge options question

[Andrew Syrewicze]

Hello all,

I followed the gentoo instructions to properly update to the new version
of GCC. I read from other posts that it isn't truly nessecary to
re-emerge any packages for this particular upgrade, but i'm still fairly
new to Gentoo so i figured i'd do it just for the practice.

so anyway,

I ran emerge -eav system followed by emerge -eav world. Needless to say
this produced several packages that needed to be rebuilt. 168 for system
and 630 for world. 

My main question is what exactly does the -e option do in emerge? 

I looked in the man page it didn't seem quite clear to me, but maybe
that's do to me still being partially noobish still. I noticed that
running emerge -av world didn't pull in nearly as many packages.

I'm just curious as i'd like a clearer understanding of how portage
works. 

Thanks!! 

--
Andy