我使用的是 14.04 beta 版，当稳定版本推出时，我认为它可能会更新到稳定版本，但现在我使用 sudo apt-get update 不断收到这些消息，使用 synaptic 时也收到类似的消息
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty Release.gpg
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty Release
Err cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/main 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
Err cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/restricted 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
Err cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/main i386 Packages
Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Err cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/restricted i386 Packages
Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/main Translation-en_US
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/main Translation-en
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/restricted Translation-en_US
Ign cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326) trusty/restricted Translation-en
Ign http://dl.google.com stable InRelease
Ign http://dl.google.com stable InRelease
Hit http://dl.google.com stable Release.gpg
Hit http://dl.google.com stable Release.gpg
Hit http://dl.google.com stable Release
Hit http://dl.google.com stable Release
Hit http://dl.google.com stable/main amd64 Packages
Hit http://dl.google.com stable/main i386 Packages
Hit http://dl.google.com stable/main amd64 Packages
Hit http://dl.google.com stable/main i386 Packages
Get:1 https://download.01.org trusty InRelease
Ign https://download.01.org trusty InRelease
Get:2 https://download.01.org trusty/main amd64 Packages/DiffIndex
Ign https://download.01.org trusty/main amd64 Packages/DiffIndex
Ign https://download.01.org trusty/main i386 Packages/DiffIndex
Ign http://dl.google.com stable/main Translation-en_US
Ign http://dl.google.com stable/main Translation-en
Ign http://dl.google.com stable/main Translation-en_US
Ign http://dl.google.com stable/main Translation-en
Ign http://archive.ubuntu.com trusty InRelease
Ign http://extras.ubuntu.com trusty InRelease
Ign http://archive.ubuntu.com trusty-updates InRelease
Ign http://archive.canonical.com trusty InRelease
Ign http://archive.ubuntu.com trusty-backports InRelease
Hit http://extras.ubuntu.com trusty Release.gpg
Hit http://archive.canonical.com trusty Release.gpg
Ign http://archive.ubuntu.com trusty-security InRelease
Hit http://extras.ubuntu.com trusty Release
Ign http://archive.ubuntu.com trusty-proposed InRelease
Hit http://archive.canonical.com trusty Release
Hit http://archive.ubuntu.com trusty Release.gpg
Hit http://extras.ubuntu.com trusty/main amd64 Packages
Hit http://archive.canonical.com trusty/partner amd64 Packages
Hit http://archive.ubuntu.com trusty-updates Release.gpg
Hit http://extras.ubuntu.com trusty/main i386 Packages
Hit http://archive.ubuntu.com trusty-backports Release.gpg
Hit http://archive.canonical.com trusty/partner i386 Packages
Hit http://archive.ubuntu.com trusty-security Release.gpg
Hit http://archive.ubuntu.com trusty-proposed Release.gpg
Hit http://archive.ubuntu.com trusty Release
Hit http://archive.ubuntu.com trusty-updates Release
Hit http://archive.ubuntu.com trusty-backports Release
Hit http://archive.ubuntu.com trusty-security Release
Hit http://archive.ubuntu.com trusty-proposed Release
Hit http://archive.ubuntu.com trusty/main Sources
Hit http://archive.ubuntu.com trusty/restricted Sources
Hit http://archive.ubuntu.com trusty/universe Sources
Hit http://archive.ubuntu.com trusty/multiverse Sources
Hit http://archive.ubuntu.com trusty/main amd64 Packages
Hit https://download.01.org trusty/main amd64 Packages
Ign http://extras.ubuntu.com trusty/main Translation-en_US
Ign http://extras.ubuntu.com trusty/main Translation-en
Ign http://archive.canonical.com trusty/partner Translation-en_US
Hit http://archive.ubuntu.com trusty/restricted amd64 Packages
Hit http://archive.ubuntu.com trusty/universe amd64 Packages
Ign http://archive.canonical.com trusty/partner Translation-en
Hit http://archive.ubuntu.com trusty/multiverse amd64 Packages
Hit http://archive.ubuntu.com trusty/main i386 Packages
Hit https://download.01.org trusty/main i386 Packages
Hit http://archive.ubuntu.com trusty/restricted i386 Packages
Hit http://archive.ubuntu.com trusty/universe i386 Packages
Hit http://archive.ubuntu.com trusty/multiverse i386 Packages
Get:3 https://download.01.org trusty/main Translation-en_US
Ign https://download.01.org trusty/main Translation-en_US
Hit http://archive.ubuntu.com trusty/main Translation-en
Ign https://download.01.org trusty/main Translation-en
Hit http://archive.ubuntu.com trusty/multiverse Translation-en
Ign http://ppa.launchpad.net saucy InRelease
Hit http://archive.ubuntu.com trusty/restricted Translation-en
Hit http://ppa.launchpad.net saucy Release.gpg
Hit http://archive.ubuntu.com trusty/universe Translation-en
Hit http://ppa.launchpad.net saucy Release
Hit http://archive.ubuntu.com trusty-updates/main Sources
Hit http://ppa.launchpad.net saucy/main amd64 Packages
Hit http://archive.ubuntu.com trusty-updates/restricted Sources
Hit http://archive.ubuntu.com trusty-updates/universe Sources
Hit http://ppa.launchpad.net saucy/main i386 Packages
Hit http://archive.ubuntu.com trusty-updates/multiverse Sources
Hit http://archive.ubuntu.com trusty-updates/main amd64 Packages
Hit http://archive.ubuntu.com trusty-updates/restricted amd64 Packages
Hit http://archive.ubuntu.com trusty-updates/universe amd64 Packages
Hit http://archive.ubuntu.com trusty-updates/multiverse amd64 Packages
Hit http://archive.ubuntu.com trusty-updates/main i386 Packages
Hit http://archive.ubuntu.com trusty-updates/restricted i386 Packages
Hit http://archive.ubuntu.com trusty-updates/universe i386 Packages
Hit http://archive.ubuntu.com trusty-updates/multiverse i386 Packages
Hit http://archive.ubuntu.com trusty-updates/main Translation-en
Hit http://archive.ubuntu.com trusty-updates/multiverse Translation-en
Ign http://ppa.launchpad.net saucy/main Translation-en_US
Ign http://ppa.launchpad.net saucy/main Translation-en
Hit http://archive.ubuntu.com trusty-updates/restricted Translation-en
Hit http://archive.ubuntu.com trusty-updates/universe Translation-en
Hit http://archive.ubuntu.com trusty-backports/main Sources
Hit http://archive.ubuntu.com trusty-backports/restricted Sources
Hit http://archive.ubuntu.com trusty-backports/universe Sources
Hit http://archive.ubuntu.com trusty-backports/multiverse Sources
Hit http://archive.ubuntu.com trusty-backports/main amd64 Packages
Hit http://archive.ubuntu.com trusty-backports/restricted amd64 Packages
Hit http://archive.ubuntu.com trusty-backports/universe amd64 Packages
Hit http://archive.ubuntu.com trusty-backports/multiverse amd64 Packages
Hit http://archive.ubuntu.com trusty-backports/main i386 Packages
Hit http://archive.ubuntu.com trusty-backports/restricted i386 Packages
Hit http://archive.ubuntu.com trusty-backports/universe i386 Packages
Hit http://archive.ubuntu.com trusty-backports/multiverse i386 Packages
Hit http://archive.ubuntu.com trusty-backports/main Translation-en
Hit http://archive.ubuntu.com trusty-backports/multiverse Translation-en
Hit http://archive.ubuntu.com trusty-backports/restricted Translation-en
Hit http://archive.ubuntu.com trusty-backports/universe Translation-en
Hit http://archive.ubuntu.com trusty-security/main Sources
Hit http://archive.ubuntu.com trusty-security/restricted Sources
Hit http://archive.ubuntu.com trusty-security/universe Sources
Hit http://archive.ubuntu.com trusty-security/multiverse Sources
Hit http://archive.ubuntu.com trusty-security/main amd64 Packages
Hit http://archive.ubuntu.com trusty-security/restricted amd64 Packages
Hit http://archive.ubuntu.com trusty-security/universe amd64 Packages
Hit http://archive.ubuntu.com trusty-security/multiverse amd64 Packages
Hit http://archive.ubuntu.com trusty-security/main i386 Packages
Hit http://archive.ubuntu.com trusty-security/restricted i386 Packages
Hit http://archive.ubuntu.com trusty-security/universe i386 Packages
Hit http://archive.ubuntu.com trusty-security/multiverse i386 Packages
Hit http://archive.ubuntu.com trusty-security/main Translation-en
Hit http://archive.ubuntu.com trusty-security/multiverse Translation-en
Hit http://archive.ubuntu.com trusty-security/restricted Translation-en
Hit http://archive.ubuntu.com trusty-security/universe Translation-en
Get:4 http://archive.ubuntu.com trusty-proposed/restricted amd64 Packages [14 B]
Get:5 http://archive.ubuntu.com trusty-proposed/multiverse amd64 Packages [14 B]
Get:6 http://archive.ubuntu.com trusty-proposed/universe amd64 Packages [34.9 kB]
Get:7 http://archive.ubuntu.com trusty-proposed/main amd64 Packages [63.9 kB]
Get:8 http://archive.ubuntu.com trusty-proposed/restricted i386 Packages [14 B]
Get:9 http://archive.ubuntu.com trusty-proposed/multiverse i386 Packages [14 B]
Get:10 http://archive.ubuntu.com trusty-proposed/universe i386 Packages [35.2 kB]
Get:11 http://archive.ubuntu.com trusty-proposed/main i386 Packages [60.8 kB]
Hit http://archive.ubuntu.com trusty-proposed/main Translation-en
Hit http://archive.ubuntu.com trusty-proposed/multiverse Translation-en
Hit http://archive.ubuntu.com trusty-proposed/restricted Translation-en
Hit http://archive.ubuntu.com trusty-proposed/universe Translation-en
Ign http://archive.ubuntu.com trusty/main Translation-en_US
Ign http://archive.ubuntu.com trusty/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/main Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-updates/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-backports/main Translation-en_US
Ign http://archive.ubuntu.com trusty-backports/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-backports/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-backports/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-security/main Translation-en_US
Ign http://archive.ubuntu.com trusty-security/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-security/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-security/universe Translation-en_US
Ign http://archive.ubuntu.com trusty-proposed/main Translation-en_US
Ign http://archive.ubuntu.com trusty-proposed/multiverse Translation-en_US
Ign http://archive.ubuntu.com trusty-proposed/restricted Translation-en_US
Ign http://archive.ubuntu.com trusty-proposed/universe Translation-en_US
Fetched 198 kB in 49s (3,992 B/s)
W: GPG error: https://download.01.org trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A902DDA375E52366
W: Failed to fetch cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326)/dists/trusty/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 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326)/dists/trusty/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
W: Failed to fetch cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326)/dists/trusty/main/binary-i386/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 14.04 LTS _Trusty Tahr_ - Beta amd64 (20140326)/dists/trusty/restricted/binary-i386/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.
知道如何解决这个问题吗？
答案1
只需注释掉文件cdrom:中包含的行，/etc/apt/sources.list
sudo sed -ri '/cdrom\:/ s/^(.*)$/#\1/g' /etc/apt/sources.list
然后更新所有存储库，
sudo apt-get update
答案2
在终端中运行此命令行：
sudo echo "deb http://archive.ubuntu.com/ubuntu/ trusty main universe restricted multiverse" > /etc/apt/sources.list; sudo apt-get update
答案3
我刚刚遇到了类似的问题，我意外删除了旧的 ppa。我发出了以下命令，它恢复了我的 ppa 并允许我使用 进行更新sudo apt-get update。以下命令是：
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys A902DDA375E52366
完成后，我就可以再次使用 sudo apt-get update 了。希望这对某些人有帮助。