Method 1: Boot to single user mode
When booting into single user mode, Linux will not mount anything. Then we can remount the / to some directory in read/write mode and then edit the /etc/fstab.1. Boot Linux into single user mode
Press ESC in the grub menu and press ‘e’ to edit the grub entry. Add single to the kernel parameter like this:
kernel /vmlinuz-2.6.32.21-166.fc12.i686 ro root=/dev/mapper/VolGroup-LogVol00 vga=792 single