I am trying to update the packages on Ubuntu 12.04 LTS, which is running on a flash drive. I tried in the command: sudo apt-get update
and receive the following error:
W: Duplicate sources.list entry cdrom://Ubuntu 12.04.3 LTS _Precise Pangolin_ - Release amd64 (20130820.1)/ precise/main i386 Packages (/var/lib/apt/lists/Ubuntu%2012.04.3%20LTS%20%5fPrecise%20Pangolin%5f%20-%20Release%20amd64%20(20130820.1)_dists_precise_main_binary-i386_Packages)
W: Duplicate sources.list entry cdrom://Ubuntu 12.04.3 LTS _Precise Pangolin_ - Release amd64 (20130820.1)/ precise/restricted i386 Packages (/var/lib/apt/lists/Ubuntu%2012.04.3%20LTS%20%5fPrecise%20Pangolin%5f%20-%20Release%20amd64%20(20130820.1)_dists_precise_restricted_binary-i386_Packages)'
How can I fix this problem so the system can update packages correctly?