Managing Path With rbenv - ruby

Question

I installed rbenv to manage my ruby installations, and then I subsequently ran gem install github-pages to get jekyll and other dependencies needed for developing a github pages site. However, now when I try to run the jekyll command I get
The program 'jekyll' is currently not installed. You can install it by typing:
sudo apt-get install jekyll
I assume this is a path issue, but I thought the path was supposed to be handled by rbenv. I also previously had the same issue when completing the same process using RVM instead of rbenv. How can I fix this?
I just tried running gem env and got the following:
RubyGems Environment:
- RUBYGEMS VERSION: 2.5.1
- RUBY VERSION: 2.3.0 (2015-12-25 patchlevel 0) [x86_64-linux]
- INSTALLATION DIRECTORY: /home/daniel/.rvm/gems/ruby-2.3.0
- USER INSTALLATION DIRECTORY: /home/daniel/.gem/ruby/2.3.0
- RUBY EXECUTABLE: /home/daniel/.rbenv/versions/2.3.0/bin/ruby
- EXECUTABLE DIRECTORY: /home/daniel/.rvm/gems/ruby-2.3.0/bin
- SPEC CACHE DIRECTORY: /home/daniel/.gem/specs
- SYSTEM CONFIGURATION DIRECTORY: /home/daniel/.rbenv/versions/2.3.0/etc
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-linux
- GEM PATHS:
- /home/daniel/.rvm/gems/ruby-2.3.0
- /home/daniel/.rvm/gems/ruby-2.3.0#global
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- "gem" => "--no-document"
- REMOTE SOURCES:
- https://rubygems.org/
- SHELL PATH:
- /home/daniel/.rbenv/versions/2.3.0/bin
- /home/daniel/.rbenv/libexec
- /home/daniel/.rbenv/plugins/ruby-build/bin
- /home/daniel/.rbenv/plugins/ruby-build/bin
- /home/daniel/.rbenv/shims
- /home/daniel/.rbenv/bin
- /opt/jdk1.8.0_65/bin/home/daniel/.rvm/gems/ruby-2.3.0/bin
- /home/daniel/.rvm/gems/ruby-2.3.0#global/bin
- /home/daniel/.rvm/rubies/ruby-2.3.0/bin
- /usr/local/sbin
- /usr/local/bin
- /usr/sbin
- /usr/bin
- /sbin
- /bin
- /usr/games
- /usr/local/games
- /home/daniel/.rvm/bin

Answer 1

You have both rbenv and RVM installed and running at the same time. Don't do that.
Per the rbenv documentation:
Compatibility note: rbenv is incompatible with RVM. Please make sure to fully uninstall RVM and remove any references to it from your shell initialization files before installing rbenv.
The why to that delves into how the shell finds commands which would be off-topic. You can research that if you're so inclined.
Should I just copy /home/daniel/.rmv/gems to /home/daniel/.rbenv/bin?
No.
"just copy" would run the risk of havoc breaking loose farther down the road.
I'd recommend temporarily disabling rbenv by commenting-out its initialization in your ~/.bash_profile, then restart your terminal session resulting in only RVM being available. Then run
gem list --no-versions > ~/rvm-gems-list
Then reenable rbenv by removing the comment mark, and comment-out the RVM initialization and restart your terminal session to give rbenv control. Run
xargs gem install --conservative < ~/rvm-gems-list
which will spin through all the gems installed in your RVM instance and let gem install any that are missing. Once that finishes you can delete the rvm-gems-list file:
rm ~/rvm-gems-list
At this point you need to remove RVM, or toggle back and forth between rbenv and RVM by alternately enabling/disabling them as you did above. You can't have them both running at the same time, and trying to remember where gems are installed will be a pain so I'd suggest sticking with one or the other.
(I use them both, only on separate systems.)