Installing Ruby gems not working with Homebrew

Question

The gems I install via sudo gem install ... can't be executed (I get a command not found).

They seem to install into /usr/local/Cellar/ which is Brew's install directory (also, the gems in /Library/Ruby/ don't work either). Is there anything else I need to do to make the gems executable? I'm using Zsh on Mac OS X 10.6 with Ruby v1.8 for the one in Brew.

EDIT: It seems to be working now. I just went out for a few hours and came back to try it again.

Bish

Maybe the path is not being passed correctly to sudo. I've seen this happen on computers not my own, where I haven't cared enough to find out how to fix it. Try doing sudo /usr/local/Cellar/ruby/bin/gem list (or something, not sure about the path... I no longer have a Mac) to see if that works. If it does, you can use that workaround until someone comes along who knows how to configure your ZSH/sudo to fix this. – Calfskin

Answer 1

Homebrew is nice. However unlike brew and npm, gem does not make aliases in /usr/local/bin automatically.

Solution

I went for a very simple approach (as of March 2020):

# Based on "`brew --prefix ruby`/bin"
export PATH=/usr/local/opt/ruby/bin:$PATH
# Based on "`gem environment gemdir`/bin"
export PATH=/usr/local/lib/ruby/gems/3.0.0/bin:$PATH

Add this to your .bashrc (or .bash_profile, .zshrc, etc.).

That's it! Now all Ruby bins and installed gems will be available from your shell!

In older versions of Homebrew (before 2017), there was a separate package for Ruby 2 called ruby20, for which you'd use the following snippet instead:

export PATH=/usr/local/opt/ruby20/bin:$PATH

This line was the only line needed at the time. But, in Ruby 2.1 the gems got moved to a separate directory. No longer under /usr/local/opt/ruby/bin, but instead at /usr/local/lib/ruby/gems/2.0.0/bin (where "2.0.0" is the last major Ruby version for Gem's purposes).

How it works

Homebrew keeps track of where it installed a package, and maintains a symbolic link for you that points there.

$ brew --prefix ruby
/usr/local/opt/ruby

$ l /usr/local/opt/ruby
/usr/local/opt/ruby@ -> ../Cellar/ruby/2.5.3_1

Effectively, adding /usr/local/opt/ruby to PATH is the same as the following:

export PATH=/usr/local/Cellar/ruby/2.5.3_1/bin:$PATH

Except, this long version hardcodes the currently installed version of Ruby and would stop working next time you upgrade Ruby.

As for Gem, the following command will tell you the exact directory Gem adds new packages to:

$ gem environment gemdir
/usr/local/lib/ruby/gems/2.7.0

Tools

These tools were meant to automatically bridge between Homebrew and Gem:

• josh/brew-gem (no longer exists)
• indirect/brewbygems (unmaintained)

I haven't used these but they might work for you.

Archway

As Laruent mentioned below $(brew --prefix ruby)/bin would probably be a better alternative. – Scrunch

I didn't use that before because brew --prefix used to be quite slow, but I see that has improved. I'll adopt it, thanks! – Archway

I think this should be export PATH="/usr/local/lib/ruby/gems/2.6.0/bin:$PATH" – Theran

This is awesome! I've used the info you've provided here, and iterated on it to produce a version that doesn't hardcode the version number: https://mcmap.net/q/65112/-installing-ruby-gems-not-working-with-homebrew – Volcano

in my case, I had to change GEM_HOME, so instead of having export PATH=/usr/local/lib/ruby/gems/2.7.0/bin:$PATH, I have export GEM_HOME="$HOME/.gem" and export PATH="$GEM_HOME/bin":$PATH – Eveleen

Important note for anyone using any version of ruby other than 2.7.0 (ie. ruby 3.0.0 in my case). Make sure you change the export PATH=/usr/local/lib/ruby/gems/2.7.0/bin:$PATH to indicate whatever version of ruby you are using. For example, for ruby 3.0.0 you need to following export PATH=/usr/local/lib/ruby/gems/3.0.0/bin:$PATH. – Idealistic

Answer 2

brew unlink ruby; brew link ruby might add symlinks to /usr/local/bin/:

$ which sass
$ brew unlink ruby; brew link ruby
Unlinking /usr/local/Cellar/ruby/2.0.0-p0... 20 links removed
Linking /usr/local/Cellar/ruby/2.0.0-p0... 31 symlinks created
$ which sass
/usr/local/bin/sass

brew --prefix ruby is still pretty slow, but you could also just add /usr/local/opt/ruby/bin to the path.

$ time brew --prefix ruby
/usr/local/opt/ruby
0.216
$ time brew --prefix ruby
/usr/local/opt/ruby
0.076
$ stat -f%Y /usr/local/opt/ruby
../Cellar/ruby/2.0.0-p0

Gossamer

This should be the accepted answer. The OP is using homebrew, so an answer solving for the particular use case (when available) is more appropriate than suggesting a different workflow. – Twinned

Answer 3

I like home brew. There's probably a better way to do this, but if you run:

gem environment

That will print out a nice list of all the relevant paths. Look for the one labeled EXECUTABLE DIRECTORY. That's the one you want to add to your path. In my case that's /usr/local/Cellar/ruby/1.9.3-p362/bin/ruby but I would imagine it would change with newer version of Ruby.

I'm using /bin/bash as my shell, but the process of adding it to your path should be pretty much the name.

I use TextWrangler (via the command line tools) to edit my .profile file. To do that, it's just:

edit ~/.profile

When your done, either close your terminal and open a new one, or run:

source ~/.profile

Percuss

I had no problem using Homebrew with gem install ruby then (after using rvm for a few years then abandoning it, but being used to non-system-wide gem installs) just gem install [gemname]. To use the gems, I added /usr/local/opt/ruby/bin to the end of my PATH variable in .bash_profile. Simple, and works for me, as I don't need gemsets or multiple Rubies. – Capacity

Answer 4

Using the info in Timo's answer, I've got this:

PATH=/usr/local/opt/ruby/bin:$PATH
GEMSDIR=$(gem environment gemdir)/bin
PATH=$GEMSDIR:$PATH
export PATH

Works for Homebrew, works for the separate gems directory, and doesn't hardcode a Ruby version.

Volcano

This fixed my MacOS Smashing dashboard issues on Mojave. Thank you! – Patrilineage

Yes! This fixed my question too—thanks so much! – Shanahan

Answer 5

You can be fine with ruby installed by homebrew too.. You just lack the functionality of custom gemsets with homebrew.

first do:

sudo nano /etc/paths

this will bring up nano editor,

then add the following to the paths:

/usr/local/Cellar/ruby/1.9.3-p194/bin

your version of ruby will probably vary.

Thats it. It should now detect your gems.

Oh, btw, you need to Ctrl+X > y > ENTER to save a file in nano.

Kangaroo

Or add PATH=/usr/local/Cellar/ruby/1.9.3-p194/bin:$PATH to your .zshrc/.bashrc file. – Dawson

update: I use chruby and ruby-install now.. and no longer need rvm.. I like this much much better! – Kangaroo

Answer 6

Instead of using => $(cd $(which gem)/..; pwd)

You could use this instead => $(brew --prefix ruby)/bin

Saki

Answer 7

I think this evolve a bit.

Just add

export PATH=/usr/local/opt/ruby/bin:$PATH

To your .bashrc (or .bash_profile, .zshrc/.bashrc, .. – whatever you use).

If you have a problem with ruby itself

brew unlink ruby
brew link ruby

Marrero