升级 OS X El Capitan 后，Time Machine 恢复下，随后因为遇到 octopress 无法更新博客问题，一番折腾 octopress 适配了 OS X El Capitan，然而事情总没有那么简单，又丢过来一个问题。
和往常一样使用 Cocoapods ，执行命令：
$ pod install
#输出信息
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/dependency.rb:296:in `to_specs': Could not find 'cocoapods' (>= 0) among 59 total gem(s) (Gem::LoadError)
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/dependency.rb:307:in `to_spec'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_gem.rb:47:in `gem'
from /usr/local/bin/pod:22:in `<main>'
查看 Ruby 版本：
$ ruby -v
ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
看来是升级 Ruby 2.2.3 导致的问题，更新下 Cocoapods 即可，更新步骤：
1、 更新 gem ，国内需切换 gem source
$ sudo gem update --system
- 切换
gem source
$ gem sources --add https://gems.ruby-china.org/ --remove https://rubygems.org/
$ gem sources -l
*** CURRENT SOURCES***
https://gems.ruby-china.org
2、 安装 cocoapods
$ sudo gem install cocoapods
$ pod setup
#mac osx 10.11 之后
$ sudo gem install -n /usr/local/bin cocoapods --pre //安装最新版本
$ sudo gem install -n /usr/local/bin cocoapods -v <version> //安装指定的 version
和安装过程是一样的，再次查看 pod 版本：
$ pod --version
0.39.0
搞定～
网友评论
Setting up CocoaPods master repo
[!] /usr/bin/git clone https://github.com/CocoaPods/Specs.git master
Cloning into 'master'...
error: RPC failed; curl 56 SSLRead() return error -9806
fatal: The remote end hung up unexpectedly
fatal: early EOF
fatal: index-pack failed
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /usr/bin/xcodeproj
怎么办？
sudo gem install cocoapods 会报错 『Operation not permitted - /usr/bin/xcodeproj』使用第一句命令就好了
/usr/local/lib/ruby/site_ruby/2.3.0/rubygems.rb:270:in `find_spec_for_exe': can't find gem cocoapods (>= 0.a) (Gem::GemNotFoundException)
from /usr/local/lib/ruby/site_ruby/2.3.0/rubygems.rb:298:in `activate_bin_path'
from /usr/local/bin/pod:22:in `<main>'
这个是什么错误？