禁用ppa源，你把你有问题的ppa源删除就正常了

W: 校验签名出错。此仓库未被更新，仍然使用以前的索引文件。GPG 错误：http://extras.ubuntu.com precise Release: 下列签名无效： BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>[$1][$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 7274A4DAE80D6BF5 Launchpad cairo-dock[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG D8AD4DE78EEBB0CA Launchpad ClipGrab PPA[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 751A20CF523884B2 Launchpad PPA for Diodon Team[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG FFB0B9D98EA3D2BF Launchpad PPA for jf[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 97F6E5D34865CF4F Launchpad OSD Lyrics[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 464AD83D4631BBEA Launchpad equinoxart[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG C2518248EEA14886 Launchpad VLC[$1]W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 10975893E549B1AC Launchpad yorba[$1]W: 无法下载 http://extras.ubuntu.com/ubuntu/dists/precise/Release [$1][$1]W: Some index files failed to download. They have been ignored, or old ones used instead.

W: 校验签名出错。此仓库未被更新，仍然使用以前的索引文件。GPG 错误：http://extras.ubuntu.com precise Release: 下列签名无效： BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>[$1][$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 7274A4DAE80D6BF5 Launchpad cairo-dock[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG D8AD4DE78EEBB0CA Launchpad ClipGrab PPA[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 751A20CF523884B2 Launchpad PPA for Diodon Team[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG FFB0B9D98EA3D2BF Launchpad PPA for jf[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 97F6E5D34865CF4F Launchpad OSD Lyrics[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 464AD83D4631BBEA Launchpad equinoxart[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG C2518248EEA14886 Launchpad VLC[$1]
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 10975893E549B1AC Launchpad yorba[$1]
W: 无法下载 http://extras.ubuntu.com/ubuntu/dists/precise/Release [$1][$1]
W: Some index files failed to download. They have been ignored, or old ones used instead.

请cat /etc/apt/sources.list

# deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/main/binary-i386/
# deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/restricted/binary-i386/
# deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ precise main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu precise main restricted
deb-src http://archive.ubuntu.com/ubuntu precise main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu precise-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu precise-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu precise universe
deb-src http://archive.ubuntu.com/ubuntu precise universe
deb http://archive.ubuntu.com/ubuntu precise-updates universe
deb-src http://archive.ubuntu.com/ubuntu precise-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://archive.ubuntu.com/ubuntu precise multiverse
deb-src http://archive.ubuntu.com/ubuntu precise multiverse
deb http://archive.ubuntu.com/ubuntu precise-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu precise-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-backports main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu precise-security main restricted
deb-src http://archive.ubuntu.com/ubuntu precise-security main restricted
deb http://archive.ubuntu.com/ubuntu precise-security universe
deb-src http://archive.ubuntu.com/ubuntu precise-security universe
deb http://archive.ubuntu.com/ubuntu precise-security multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu precise partner
# deb-src http://archive.canonical.com/ubuntu precise partner
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main


yuqiang@yu:~$ sudo add-apt-repository -r ppa:http://extras.ubuntu.com precise Release
[sudo] password for yuqiang:
Error: need a repository as argument
yuqiang@yu:~$ sudo add-apt-repository -r ppa:ubuntu.com precise ReleaseError: need a repository as argument
yuqiang@yu:~$ sudo add-apt-repository -r ppa:precise Release/ppa
Error: need a repository as argument


deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main
删掉

W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 7274A4DAE80D6BF5 Launchpad cairo-dock
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG D8AD4DE78EEBB0CA Launchpad ClipGrab PPA
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 751A20CF523884B2 Launchpad PPA for Diodon Team
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG FFB0B9D98EA3D2BF Launchpad PPA for jf
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 97F6E5D34865CF4F Launchpad OSD Lyrics
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 464AD83D4631BBEA Launchpad equinoxart
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG C2518248EEA14886 Launchpad VLC
W: GPG 错误：http://ppa.launchpad.net precise Release: 下列签名无效： BADSIG 10975893E549B1AC Launchpad yorba