After upgrading from Yosemite to El Capitan, one of several issues I had was that Jekyll no longer worked. Similar to the issue I had with LaTex, this seems to be related to the new feature in El Capitan known as System Integrity Protection.

The error message I received stated:

gem install jekyll
ERROR:  While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.


This can be overcome by installing a new version of ruby using homebrew, and then installing jekyll. @chmaynard was kind enough to put togher a nice description of the steps necessary, which are described below for convenience:

• Install the Xcode command line utilities xcode-select –install
• Install Homebrew: ruby -e "\$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
• Install the latest ruby via homebrew: brew install ruby
• Install the latest Jekyll: gem install jekyll`

After that, jekyll worked for me without further problems.