Ch. 3 Grub- editing grub.cfg on centos 7 during boot
Just an FYI in case anyone else has this issue with the Ch 3 labs on GRUB. I couldnt figure out where to edit the line to add the number 3 to boot to runlevel 3 non graphical mode. Some google searching found a page that helped a bit. If you are running Centos 7, you boot up, and stop at the GRUB menu, select the kernel you want to boot, hit 'e'- and now look for the following line and add the number 3 after "/centos-root".
linux16 /vmlinuz-3.10.0-229.1.2.el7.x86_64 root=/dev/mapper/centos-root 3 ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=en_US.UTF-8 systemd.debug initrd16 /initramfs-3.10.0-229.1.2.el7.x86_64.img
There may be other things after "/centos-root" but just put a space at the end and add the number 3 in between.
If I have made any mistakes with this info let me know.