##GUI to CLI single boot.
When you are at the GRUB menu where you select which OS to boot (if this menu don’t appear, press ESC while you get the “Booting CentOS in X seconds”), press e to edit your boot commands. You should see a screen like this: (parameters may vary)
##GUI to CLI permanent boot.
Look for the line that begins with kernel. Choose it and then press e again. You will be at a simple editor, add 3 to the end of this line. This means booting in runlevel 3, which is text-mode only.
To make this stick: edit /etc/inittab and look for a line that begin with id:5. Replace the 5 in that line by 3. You can find a brief description of runlevels here, but shortly:
- Runlevel 0 and 6: halt and reboot the machine, respectively.
- Runlevel 1: No services running, only root can login.
- Runlevel 2: Users can login but no networking.
- Runlevel 3: Networking and text-mode.
- Runlevel 4: unused.
- Runlevel 5: GUI.