sudo apt-get update error to fix grub menu

Question

I have installed Ubuntu 13.10 on my PC as dual-boot with Windows 8. However the grub menu doesn't apper, and to fix that I'm supposed to run the sudo apt-get update command which is giving error. I'm a newbie to the world of linux, so please help me out here.

Error:

W: Failed to fetch cdrom://Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)/dists/saucy/main/binary-amd64/Packages  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
W: Failed to fetch cdrom://Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)/dists/saucy/restricted/binary-amd64/Packages  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
E: Some index files failed to download. They have been ignored, or old ones used instead.

No, just sudo apt-get update. Should I use sudo apt-get update grub? — Simran Kapur, Mar 24 '15 at 20:34
No. That's not the proper way to update GRUB. Updating GRUB isn't an action that's controlled by APT. You have to run sudo update-grub for that. — Terrance8D, Mar 24 '15 at 20:36
/usr/sbin/grub-probe: error: failed to get canonical path of /cow. — Simran Kapur, Mar 24 '15 at 20:45

score 1 · Answer 1 · edited Mar 24 '15 at 21:30

1

Those warnings mean that some cdroms are selected as repositories and when you ran apt-get update, they were not mounted, so it could not find them.

There is an option in your System settings > Software & Updates where you can (un)check whether you want to have your installation media as repository or not. I would advise you tu uncheck it. In my case, it's the option at the bottom of the window, but it might look different in other versions and languages.

Screenshot (German) of the Software&Updates window

You could also manually edit the file /etc/apt/sources.list and convert the lines starting with cdrom to comments (writing an # before them), that should do the same trick.

But except that you should always keep your system up to date (with sudo apt-get update && sudo apt-get upgrade or any other package manager), this has nothing to do with GRUB. The command to create a fresh grub.conf and update the OS list is sudo update-grub.

If you want to run boot-repair you have to add its PPA first and install it. This is achieved by the following commands:

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair
boot-repair

Explanation:

adds the PPA to the repository list. apt-get can't find it otherwise.
updates the index of available software from your repos
this command actually installs boot-repair
now it's time to launch it!

edited Mar 24 '15 at 21:30

muru

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answered Mar 24 '15 at 20:41

Byte Commander

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Could you elaborate on the unchecking of "installation media being a repository" part, I can't find the option in Software & Updates. – Simran Kapur Mar 24 '15 at 20:45
Would a German screenshot help you? – Byte Commander Mar 24 '15 at 20:47
Sure, something is better than nothing. – Simran Kapur Mar 24 '15 at 20:47
Also, my /etc/apt/sources.list has the following data:
#deb cdrom:[Linux Mint 17 Qiana - Release amd64 20140623]/ trusty contrib main non-free
– Simran Kapur Mar 24 '15 at 20:49
I added a screenshot. The line you quoted is already commented out, so it would not get processed. There must be another one... – Byte Commander Mar 24 '15 at 20:57
No, thats the only line there. – Simran Kapur Mar 24 '15 at 21:00
I saw the screenshot and what I understand is that I have to uncheck the last checkbox from the bottom. Is that right? – Simran Kapur Mar 24 '15 at 21:00
Okay, so I unchecked it and sudo apt-get update worked without errors. But then to repair grub menu, the command I have to use is sudo apt-get install -y boot-repair && boot-repair which is giving error. error: E: Unable to locate package boot-repair – Simran Kapur Mar 24 '15 at 21:11
You probably forgot to add the PPA as boot-repair is not located in the standard repositories. If not, maybe you forgot to update the index files... I added a paragraph to my answer. – Byte Commander Mar 24 '15 at 21:29

sudo apt-get update error to fix grub menu

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