How to find where gem files are installed - ruby

Question

I can finds gems that are installed using gem list, but it doesn't show me where the gems are installed.
How can I find where the gems are, and how can I know before installing a gem where it will be installed?

Answer 1

Use gem environment to find out about your gem environment:
RubyGems Environment:
- RUBYGEMS VERSION: 2.1.5
- RUBY VERSION: 2.0.0 (2013-06-27 patchlevel 247) [x86_64-darwin12.4.0]
- INSTALLATION DIRECTORY: /Users/ttm/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0
- RUBY EXECUTABLE: /Users/ttm/.rbenv/versions/2.0.0-p247/bin/ruby
- EXECUTABLE DIRECTORY: /Users/ttm/.rbenv/versions/2.0.0-p247/bin
- SPEC CACHE DIRECTORY: /Users/ttm/.gem/specs
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-darwin-12
- GEM PATHS:
- /Users/ttm/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0
- /Users/ttm/.gem/ruby/2.0.0
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- https://rubygems.org/
- SHELL PATH:
- /Users/ttm/.rbenv/versions/2.0.0-p247/bin
- /Users/ttm/.rbenv/libexec
- /Users/ttm/.rbenv/plugins/ruby-build/bin
- /Users/ttm/perl5/perlbrew/bin
- /Users/ttm/perl5/perlbrew/perls/perl-5.18.1/bin
- /Users/ttm/.pyenv/shims
- /Users/ttm/.pyenv/bin
- /Users/ttm/.rbenv/shims
- /Users/ttm/.rbenv/bin
- /Users/ttm/bin
- /usr/local/mysql-5.6.12-osx10.7-x86_64/bin
- /Users/ttm/libsmi/bin
- /usr/local/bin
- /usr/bin
- /bin
- /usr/sbin
- /sbin
- /usr/local/bin
Notice the two sections for:
INSTALLATION DIRECTORY
GEM PATHS

Answer 2

I found it useful to get a location of the library file with:
gem which *gemname*

Answer 3

After installing the gems, if you want to know where a particular gem is. Try typing:
gem list
You will be able to see the list of gems you have installed. Now use bundle show and name the gem you want to know the path for, like this:
bundle show <gemName>
Or (as of younger versions of bundler):
bundle info <gemName>

Answer 4

To complete other answers, the gem-path gem can find the installation path of a particular gem.
Installation:
gem install gem-path
Usage:
gem path rails
=> /home/cbliard/.rvm/gems/ruby-2.1.5/gems/rails-4.0.13
gem path rails '< 4'
=> /home/cbliard/.rvm/gems/ruby-2.1.5/gems/rails-3.2.21
This is really handy as you can use it to grep or edit files:
grep -R 'Internal server error' "$(gem path thin)"
subl "$(gem path thin)"

Answer 5

You can check it from your command prompt by running gem help commands and then selecting the proper command:
kirti#kirti-Aspire-5733Z:~$ gem help commands
GEM commands are:
build Build a gem from a gemspec
cert Manage RubyGems certificates and signing settings
check Check a gem repository for added or missing files
cleanup Clean up old versions of installed gems in the local
repository
contents Display the contents of the installed gems
dependency Show the dependencies of an installed gem
environment Display information about the RubyGems environment
fetch Download a gem and place it in the current directory
generate_index Generates the index files for a gem server directory
help Provide help on the 'gem' command
install Install a gem into the local repository
list Display gems whose name starts with STRING
lock Generate a lockdown list of gems
mirror Mirror all gem files (requires rubygems-mirror)
outdated Display all gems that need updates
owner Manage gem owners on RubyGems.org.
pristine Restores installed gems to pristine condition from
files located in the gem cache
push Push a gem up to RubyGems.org
query Query gem information in local or remote repositories
rdoc Generates RDoc for pre-installed gems
regenerate_binstubs Re run generation of executable wrappers for gems.
search Display all gems whose name contains STRING
server Documentation and gem repository HTTP server
sources Manage the sources and cache file RubyGems uses to
search for gems
specification Display gem specification (in yaml)
stale List gems along with access times
uninstall Uninstall gems from the local repository
unpack Unpack an installed gem to the current directory
update Update installed gems to the latest version
which Find the location of a library file you can require
yank Remove a specific gem version release from
RubyGems.org
For help on a particular command, use 'gem help COMMAND'.
Commands may be abbreviated, so long as they are unambiguous.
e.g. 'gem i rake' is short for 'gem install rake'.
kirti#kirti-Aspire-5733Z:~$
Now from the above I can see the command environment is helpful. So I would do:
kirti#kirti-Aspire-5733Z:~$ gem help environment
Usage: gem environment [arg] [options]
Common Options:
-h, --help Get help on this command
-V, --[no-]verbose Set the verbose level of output
-q, --quiet Silence commands
--config-file FILE Use this config file instead of default
--backtrace Show stack backtrace on errors
--debug Turn on Ruby debugging
Arguments:
packageversion display the package version
gemdir display the path where gems are installed
gempath display path used to search for gems
version display the gem format version
remotesources display the remote gem servers
platform display the supported gem platforms
<omitted> display everything
Summary:
Display information about the RubyGems environment
Description:
The RubyGems environment can be controlled through command line arguments,
gemrc files, environment variables and built-in defaults.
Command line argument defaults and some RubyGems defaults can be set in a
~/.gemrc file for individual users and a /etc/gemrc for all users. These
files are YAML files with the following YAML keys:
:sources: A YAML array of remote gem repositories to install gems from
:verbose: Verbosity of the gem command. false, true, and :really are the
levels
:update_sources: Enable/disable automatic updating of repository metadata
:backtrace: Print backtrace when RubyGems encounters an error
:gempath: The paths in which to look for gems
:disable_default_gem_server: Force specification of gem server host on
push
<gem_command>: A string containing arguments for the specified gem command
Example:
:verbose: false
install: --no-wrappers
update: --no-wrappers
:disable_default_gem_server: true
RubyGems' default local repository can be overridden with the GEM_PATH and
GEM_HOME environment variables. GEM_HOME sets the default repository to
install into. GEM_PATH allows multiple local repositories to be searched for
gems.
If you are behind a proxy server, RubyGems uses the HTTP_PROXY,
HTTP_PROXY_USER and HTTP_PROXY_PASS environment variables to discover the
proxy server.
If you would like to push gems to a private gem server the RUBYGEMS_HOST
environment variable can be set to the URI for that server.
If you are packaging RubyGems all of RubyGems' defaults are in
lib/rubygems/defaults.rb. You may override these in
lib/rubygems/defaults/operating_system.rb
kirti#kirti-Aspire-5733Z:~$
Finally to show you what you asked, I would do:
kirti#kirti-Aspire-5733Z:~$ gem environment gemdir
/home/kirti/.rvm/gems/ruby-2.0.0-p0
kirti#kirti-Aspire-5733Z:~$ gem environment gempath
/home/kirti/.rvm/gems/ruby-2.0.0-p0:/home/kirti/.rvm/gems/ruby-2.0.0-p0#global
kirti#kirti-Aspire-5733Z:~$

Answer 6

You can trick gem open into displaying the gem path:
VISUAL=echo gem open gem-name
Example:
VISUAL=echo gem open rails
=> /usr/local/opt/asdf/installs/ruby/2.4.3/lib/ruby/gems/2.4.0/gems/rails-5.1.4
It just works, and no third party gem is necessary.

Answer 7

gem env works just like gem environment. Saves some typing.
# gem env
RubyGems Environment:
- RUBYGEMS VERSION: 2.0.14
- RUBY VERSION: 2.0.0 (2014-02-24 patchlevel 451) [i686-linux]
- INSTALLATION DIRECTORY: /usr/local/lib/ruby/gems/2.0.0
- RUBY EXECUTABLE: /usr/local/bin/ruby
- EXECUTABLE DIRECTORY: /usr/local/bin
- RUBYGEMS PLATFORMS:
- ruby
- x86-linux
- GEM PATHS:
- /usr/local/lib/ruby/gems/2.0.0
- /root/.gem/ruby/2.0.0
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- https://rubygems.org/

Answer 8

The gem env lists where gems can be installed, but this can be 10 or more locations. If you want to know where a particular gem is installed, you can execute:
gem list -d <gemname>
Example output:
tilt (2.0.9)
Author: Ryan Tomayko
Homepage: http://github.com/rtomayko/tilt/
License: MIT
Installed at: /opt/rubies/ruby-2.5.3/lib/ruby/gems/2.5.0
Generic interface to multiple Ruby template engines

Answer 9

if you are using rvm tool you can run this command to print gem path:
rvm gemdir
OR
echo $GEM_HOME

Answer 10

This works and gives you the installed at path for each gem. This super helpful when trying to do multi-stage docker builds.. You can copy in the specific directory post-bundle install.
bash-4.4# gem list -d
Output::
aasm (5.0.6)
Authors: Thorsten Boettger, Anil Maurya
Homepage: https://github.com/aasm/aasm
License: MIT
Installed at: /usr/local/bundle
State machine mixin for Ruby objects

Answer 11

One can go to rails console and do
Gem.bin_path('<gem-name>', '<gem-executable-name>')
It returns exact path to the gem file executable.
Ref: https://www.rubydoc.info/github/rubygems/rubygems/Gem.bin_path