How to write on a file?

[M1ck4el]

Hi,
I have troubles to write on my file /etc/lightdm/lightdm.conf
I typed sudo nano /etc/lightdm/lightdm.conf to open my file but I can only read (and not write).

This didn't work
http://ubuntuforums.org/showthread.php?t=2141347

but it's true, I am in recovery mode

[Elfy]

If you've only got read access then I'd say you've not mounted it properly to enable write.

mount -o rw,remount /

IF you still have issues - run one of the other commands in the recovery menu - grub update for instance, then try the root terminal again

[Korkel]

Run the following script, it will open the requested file as root so you can edit it.
gedit-su.sh
Make sure that you allow the file to run in a terminal.

Try also advice given above.

[ajgreeny]

Recovery mode by default mounts the filesystem now as read only (to save potentially damaging activity by users who don't know what they're doing, I think), so to make any changes to the system files you need to run that command mentioned by Elfy.

[Elfy]

Run the following script, it will open the requested file as root so you can edit it.
gedit-su.sh
Make sure that you allow the file to run in a terminal.

Try also advice given above.

How does a script that includes running gedit help?

In addition the thread has no prefix - what about if they are using Xubuntu, Lubuntu, Kubuntu ?

Please stay on topic for the thread - which is running nano in recovery mode - there would be no need for sudo anyway once the filesystem is mounted.