在Ubuntu 14.04.4上安装rvm rails：
\curl -L https://get.rvm.io | bash -s stable --ruby
输出显示：
rvm 1.26.11 (latest) by Wayne E. Seguin <wayneeseguin@gmail.com>, Michal Papis <mpapis@gmail.com> [https://rvm.io/]
Searching for binary rubies, this might take some time.
Found remote file https://rvm_io.global.ssl.fastly.net/binaries/ubuntu/14.04/x86_64/ruby-2.2.1.tar.bz2
最后错误：
The following packages have unmet dependencies:
libffi-dev : Depends: libffi6 (= 3.1~rc1+r3.0.13-12) but 3.1~rc1+r3.0.13-12ubuntu0.1 is to be installed
我试过了：
sudo apt-get update
sudo apt-get upgrade
\curl -L https://get.rvm.io | bash -s stable --ruby
没有解决。
我的/etc/apt/sources.list看起来像这样：
deb http://archive.ubuntu.com/ubuntu trusty main multiverse universe restricted
deb http://archive.ubuntu.com/ubuntu trusty-security main multiverse universe restricted
根据我搜索的内容，我需要下载3.1~rc1+r3.0.13-12ubuntu0.1包并手动安装？如果是这种情况我该怎么做？
此外，我想了解为什么这个软件包不是最新版本 - 可能是一个愚蠢的问题，但我不明白可能是什么原因？
使用apt-get安装这些软件包：
$ sudo apt-get install libffi6
libffi6 is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ sudo apt-get install libffi-dev
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libffi-dev : Depends: libffi6 (= 3.1~rc1+r3.0.13-12) but 3.1~rc1+r3.0.13-12ubuntu0.1 is to be installed
E: Unable to correct problems, you have held broken packages.
答案 0 :(得分：2)
我最终使用aptitude并选择非默认选项来降级libffi6包以允许安装libffi-dev：
sudo aptitude install libffi-dev
答案 1 :(得分：1)
尝试安装libffi6。
apt-get install libffi6
如果不起作用，请尝试这样：
将deb http://cz.archive.ubuntu.com/ubuntu trusty main添加到/etc/apt/sources.list
然后：
apt-get update && apt-get upgrade
apt-get install libffi6