[CentOS] how to 'yum update' in a %post

> you need to run this without the --nochroot option, there is no yum
> included in the installer system, and the only yum you will get working
> is the one inside the chroot.

OK thanks makes sense - however is there anyway to make some things run 
with --nochroot and others with it? Just that there is other things 
allready going on that need the --nochroot

> also, what made you install bash in /usr/local/bin ????

i didn't - taken over systems and when i check a system that is allready 
kickstarted it says that bash is in /usr/local/bin

thanks