我看到很多有趣的程序只能通过向系统添加“PPA”来获得，但是，如果我理解正确，我们应该留在官方“存储库”中以将软件添加到我们的系统中。
新手有什么方法可以知道“PPA”是否安全或是否应该避免？用户在处理 PPA 时应该了解哪些提示？
我最近在 Ubuntu 12.04 beta 上从 webupd8ppa 安装了一个 oracle jdk，但显然它没有成功，现在它在我每次更新或安装时都给我错误，即使在从我的来源停用 ppa 之后也是如此。
这是我尝试从 USC 卸载时得到的结果：
installArchives() failed: (Reading database ...
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading …我尝试从 安装 Sun JDK sudo add-apt-repository ppa:eugenesan/java，但失败并显示以下内容：
Downloading...
--2012-05-05 15:50:09-- http://download.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-x64.tar.gz
Resolving download.oracle.com (download.oracle.com)... 80.239.230.162
Connecting to download.oracle.com (download.oracle.com)|80.239.230.162|:80... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-x64.tar.gz [following]
--2012-05-05 15:50:09-- https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-x64.tar.gz
Resolving edelivery.oracle.com (edelivery.oracle.com)... 2.17.254.174
Connecting to edelivery.oracle.com (edelivery.oracle.com)|2.17.254.174|:443... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: http://download.oracle.com/errors/download-fail-1505220.html [following]
--2012-05-05 15:50:09-- http://download.oracle.com/errors/download-fail-1505220.html
Connecting to download.oracle.com (download.oracle.com)|80.239.230.162|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 5307 (5.2K) [text/html]
Saving to: `./jdk-7u3-linux-x64.tar.gz'
0K ..... 100% …