'sudo gem install' or 'gem install' and gem locations - ruby-on-rails

Question

Running 'sudo gem list --local' and 'gem list --local' give me differing results. My gem path is set to my home folder and only contains the gems from 'gem list --local'.
It's probably not good to have gems installed in different directories on my computer, so should I have the gem path set differently, and should I always use sudo when installing something?
my ~/.profile
export PATH=/opt/local/bin:/opt/local/sbin:$PATH
export PATH="/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH"
~/.bash_profile is empty.

Answer 1

You can install gems in your local environment (without sudo) with
gem install --user-install <gemname>
I recommend that so you don't mess with your system-level configuration even if it's a single-user computer.
You can check where the gems go by looking at gempaths with gem environment. In my case it's "~/.gem/ruby/1.8".
If you need some binaries from local installs added to your path, you can add something to your bashrc like:
if which ruby >/dev/null && which gem >/dev/null; then
PATH="$(ruby -r rubygems -e 'puts Gem.user_dir')/bin:$PATH"
fi
(from http://guides.rubygems.org/faqs/#user-install)

Answer 2

Contrary to all the other posts I suggest NOT using sudo when installing gems.
Instead I recommend you install RVM and start a happy life with portable gem homes and different version of Ruby all living under one roof.
For the uninitiated, from the documentation:
RVM is a command line tool which allows us to easily install, manage and work with multiple ruby environments and sets of gems.
The reason why installing gems with sudo is worse than just gem install is because it installs the gems for ALL USERS as root. This might be fine if you're the only person using the machine, but if you're not it can cause weirdness.
If you decide you want to blow away all your gems and start again it's much easier, and safer, to do so as a non-root user.
If you decide you want to use RVM then using sudo will cause all kinds of weirdness because each Ruby version you install through RVM has its own GEM_HOME.
Also, it's nice if you can make your development environment as close to your production environment as possible, and in production you'll most likely install gems as a non-root user.

Answer 3

Better yet, put --user-install in your ~/.gemrc file so you don't have to type it every time
gem: --user-install

Answer 4

In case you
installed ruby gems with sudo
want to install gems without sudo
don't want to install rvm/rbenv
add the following to your .bash_profile :
export GEM_HOME=/Users/‹your_user›/.gem
export PATH="$GEM_HOME/bin:$PATH"
Open a new tab in Terminal OR source ~/.bash_profile and you're good to go!

Answer 5

sudo gem install --no-user-install <gem-name>
will install your gem globally, i.e. it will be available to all user's contexts.

Answer 6

Related (for bundler users), if you want a lighter alternative to RVM which will put everything in a user-specific well known directory, I recommend using:
bundle install --path $HOME/.gem
if you want to install gems to the same place that
gem install --user-install GEMNAME
will install them, .gem/ruby/RUBYVERSION in your homedir. (See the other comment on this question about --user-install.)
This will make the gems visible to gem list, uninstallable via gem uninstall, etc. without needing sudo access. Runnable scripts installed by gem or bundler can be put into your path by adding
$HOME/.gem/ruby/RUBYVERSION/bin
to your $PATH. gem itself tells you about this if it isn't set when you do gem install --user-install.

Answer 7

You can install gems into a specific folder (example vendor/) in your Rails app using :
bundle install --path vendor

Answer 8

Installing Ruby gems on a Mac is a common source of confusion and frustration. Unfortunately, most solutions are incomplete, outdated, and provide bad advice. I'm glad the accepted answer here says to NOT use sudo, which you should never need to do, especially if you don't understand what it does. While I used RVM years ago, I would recommend chruby in 2020.
Some of the other answers here provide alternative options for installing gems, but they don't mention the limitations of those solutions. What's missing is an explanation and comparison of the various options and why you might choose one over the other. I've attempted to cover most common scenarios
in my definitive guide to installing Ruby gems on a Mac.