错误：
autoroot@autoroot:/etc/apt/sources.list.d$ sudo apt-get install python-xlib
[sudo] password for autoroot:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
python-support
The following NEW packages will be installed:
python-support python-xlib
0 upgraded, 2 newly installed, 0 to remove and 50 not upgraded.
Need to get 191 kB of archives.
After this operation, 1,080 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
python-support python-xlib
Install these packages without verification [y/N]? y
Err http://repo.iitd.ernet.in/ubuntu/ precise/universe python-support all 1.0.14ubuntu2
501 Not Implemented
Err http://repo.iitd.ernet.in/ubuntu/ precise/universe python-xlib all 0.14+20091101-1
501 Not Implemented
Failed to fetch http://repo.iitd.ernet.in/ubuntu/pool/universe/p/python-support/python-support_1.0.14ubuntu2_all.deb 501 Not Implemented
Failed to fetch http://repo.iitd.ernet.in/ubuntu/pool/universe/p/python-xlib/python-xlib_0.14+20091101-1_all.deb 501 Not Implemented
N: Ignoring 'build' in directory '/etc/apt/sources.list.d/' as it is not a regular file
N: Ignoring 'build' in directory '/etc/apt/sources.list.d/' as it is not a regular file
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
autoroot@autoroot:/etc/apt/sources.list.d$
以下是我的资料来源
$cat /etc/apt/sources.list
deb http://repo.iitd.ernet.in/ubuntu precise main restricted universe multiverse
deb-src http://repo.iitd.ernet.in/ubuntu precise main restricted universe multiverse
deb http://repo.iitd.ernet.in/ubuntu precise-proposed main restricted universe multiverse
deb-src http://repo.iitd.ernet.in/ubuntu precise-proposed main restricted universe multiverse
deb http://repo.iitd.ernet.in/ubuntu precise-updates main restricted universe multiverse
deb-src http://repo.iitd.ernet.in/ubuntu precise-updates main restricted universe multiverse
deb http://repo.iitd.ernet.in/ubuntu precise-security main restricted universe multiverse
deb-src http://repo.iitd.ernet.in/ubuntu precise-security main restricted universe multiverse
deb http://repo.iitd.ernet.in/ubuntu precise-backports main restricted universe multiverse
deb-src http://repo.iitd.ernet.in/ubuntu precise-backports main restricted universe multiverse
deb http://repo.iitd.ernet.in/ubuntupartner precise partner
deb-src http://repo.iitd.ernet.in/ubuntupartner precise partner
autoroot@autoroot:~/Desktop$ tree /etc/apt/sources.list.d/
/etc/apt/sources.list.d/
|-- dropbox.list
|-- dropbox.list.save
|-- fkrull-deadsnakes-python2_7-precise.list
|-- fkrull-deadsnakes-python2_7-precise.list.save
|-- ia32-libs-raring.list
|-- ia32-libs-raring.list.save
|-- kivy-team-kivy-precise.list
|-- kivy-team-kivy-precise.list.save
`-- webupd8team-sublime-text-3-precise.list
0 directories, 9 files
sudo apt-get update 的输出 http://paste.ubuntu.com/16275264/
还请注意，我支持机构代理。