When we have entered the chroot'ed environment in the next section we want to export a couple of environment variables in that shell such as PS1, PATH and others variables you want to have set. For that purpose we'll create the $LFS/root/.bash_profile file which will be read by bash when we enter the chroot environment.
Create a new file $LFS/root/.bash_profile by running the following.
cat > $LFS/root/.bash_profile << "EOF"
# Begin /root/.bash_profile
PS1='\u:\w\$ '
PATH=/bin:/usr/bin:/sbin:/usr/sbin
export PS1 PATH
# End /root/.bash_profile
EOF
You can add more environment variables,aliases and whatever else you need/want at your own discretion as you deem them necessary.