How to change "read-only" file at root prompt [duplicate]

Possible Duplicate:
How do I change file system in Ubuntu11.10 recovery mode to read-write mode

After blank screen, need to change some settings in xorg.conf

Logged in at root prompt through recovery mode.

Unable to change file read-only message.

How to change the file? Thanks.

Solution 1:

You must first mount the drive as read/write using the Recovery Menu option, then drop to the root shell (with networking if needed).

Everything should work then.

For Ubuntu 14.04 and higher, there is no option for read/write. Instead, enable-networking option will mount the system in read/write mode.