Removing all installed Gems and starting over - ruby

Question

I recently started learning Ruby and Ruby on Rails, and have watched a plethora of getting started materials. I have been finding lately that I keep getting errors where gems won't install or they will be installed but they can't be used for some reason, and I have decided that I want to remove everything down to once again just having Ruby installed and start over with the installation. One training video had me install most of my gems with RVM, so I don't know if that changes anything.
So in short my question is "How to I get rid of RVM, Rubygems, and all installed Gems so that I can start over with just Ruby?"
Edit: I am on Mac OS 10.6

Answer 1

gem uninstall -aIx
Uninstalls all gems without prompt.
Options
-a, --[no-]all Uninstall all matching versions
-I, --[no-]ignore-dependencies Ignore dependency requirements while
uninstalling
-x, --[no-]executables Uninstall applicable executables without
confirmation

Answer 2

From the RVM support site:
RVM installs everything into ~/.rvm.
To remove RVM from your system run 'rm
-rf ~/.rvm'. You may have one additional config file in ~/.rvmrc and
of course the RVM hook in your
bash/zsh startup files.
So, just go to the command line and type rm -rf ~/.rvm
All the installed gems are in the ~/.rvm folders, so doing the above will remove the gems and installed rubies in one go.
Gems you added pre-RVM with the default ruby install can be removed by typing this at the command prompt:
for x in `gem list --no-versions`; do gem uninstall $x -a -x -I; done

Answer 3

For Windows and Unix copy/paste in command prompt (Ruby 1.9.x).
ruby -e "`gem list`.split(/$/).each { |line| puts `gem uninstall -Iax #{line.split(' ')[0]}` unless line.strip.empty? }"

Answer 4

using RVM, you could just type...
rvm gemset empty GEMSET
where GEMSET is the gemset which you would like to empty. then...
install bundle
yum install bundler and finally
bundle install

Answer 5

rvm implode (see cli docs) seems to work - and it even tells you where to look at for leftovers

Answer 6

This is work for me on Ubuntu 16.04. For me, when I was executing
command rails -v it throw errors because of NameError. I have
installed 3 version of rails (4.2.0, 4.2.6, 5.0.0.1). I was trying
to uninstall unnecessary gem using command gem uninstall rails -v
version number but I won't able to, but I find a way to solve
this problem. In order to uninstall all gems, you have to loop
through all entries in gem list with bash scripting. This method is
very inconvenient. Thanks to Rubygems 2.1.0, you now could do it
with one command.
STEP - 1
Firstly, please make sure you upgrade your Rubygems to 2.1.0 or
newer. For this run this command (Incase you are working on an older
version. You can check your gem version using this command any one
of them gem -v or gem --version)
gem update --system
gem --version
STEP - 2
Run this command in you terminal
gem uninstall --all
Step - 3
Install gem bundles (it is not necessary I think just for
precautions)
gem install bundle
Step - 4
Install the rails on your system using this command
gem install rails -v specific version you want to install you can check the rails version on the official site rails all versions
example :- I have installed rails 4.2.6
version, you install as per requirement.
gem install rails -v 4.2.6
Step - 5
Finally check the version of installed rails framework application
by Using basic command rails -v. It will echoed the current
version of rails frameworks. Enjoy :)
References
http://ruby-journal.com/how-to-uninstall-all-ruby-gems/
http://guides.rubyonrails.org/v4.1/getting_started.html

Answer 7

Step 1:
I first kept running into an error that said:
You don't have write permissions for the /usr/bin directory
To get permission, I became a root user with (this is potentially dangerous for reasons beyond my current understanding):
sudo -s
Credit
Step 2:
Then, I kept running into an error that said:
[gem] cannot be uninstalled because it is a default gem
This allowed me to uninstall everything:
for i in `gem list --no-versions`; do gem uninstall -aIx $i; done
Credit

Answer 8

FWIW, there are some weird cases where gems are installed but not really installed:
This should do the trick reasonably reliably.
gem uninstall -Iax `gem list | grep default | awk '{print $1}'`