Arch linux : pacman does not work

view story

http://unix.stackexchange.com – I have Ubuntu installed on my computer. I decided to install Arch linux, but I skipped the part about Grub installation as it is already installed. Seeing that Arch does not show up in Grub's menu list, I decided to install it in Arch. I mounted Arch's partition in Ubuntu and I chrooted into it. I issued the command pacman -S grub-bios and got the following : error: could not open file: /etc/mtab: No such file or directory error: could not determine filesystem mount points error: failed to commit transaction (unexpected error) Errors occurred, no packages were upgraded. /etc/mtab is a symli (HowTos)