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I'm running Ubuntu on a live usb drive and every time I boot, the apt line cdrom://Ubuntu 11.10 _Oneiric Ocelot_ - Release amd64 (20111012)/ oneiric/main i386 Packages and another similar apt line (also sourced from the cdrom) get inserted in the sources.list file. And then I get that warning, which is annoying because I can't proceed with updates and installations unless that warning is rectified.

I have noticed that in one of the start-up scripts, the following lines are printed (not sure about the capitalization):

Writing new source list
Source list entries for this disc are

and then the above apt lines.

I don't know this is a lead to what's causing the duplicate entries. Also, I don't even want any cdrom to be in the sources.list file. Everytime I delete them whenever I get that warning when attempting to update/install and everytime I reboot, they come back again. Your help is appreciated.

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up vote 0 down vote accepted

It might be worth trying the GUI tools that Ubuntu offers to see if they are smart enough to address the script that is overriding your changes.

This link addresses adding things like CD sources via Ubuntu's software manager, but I'm sure you can figure out how to use the instructions to remove it instead.

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Can you tell me more about these GUI tools? – ladaghini Mar 18 '12 at 11:31
I'm talking generally, but things like Synaptic and Ubuntu's software tool in the Applications menu. I don't recall it's name. – flickerfly Apr 22 '12 at 19:04

I had the same, but found the answer here:

Duplicate sources.list entry but cannot find the duplicates?

Above resumed:


sudo cp /etc/apt/sources.list /etc/apt/sources.list.old


sudo rm /etc/apt/sources.list

run sudo apt-get update to recreate the source.list

workerd like a charm for me, I tried all kind of things, also a program y-ppa, which kept saying no duplicated found.

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