为什么不使用python-apt模块例如

Why not use the python-apt module eg.

import apt
cache=apt.Cache()
cache.update()
cache.open(None)
cache.upgrade()
for pkg in cache.getChanges():
    print pkg.sourcePackageName, pkg.isUpgradeable

还阅读了badp评论中的链接

also read the link in badp's comment