gem env列出了可以安装宝石的位置，但可以是10个或更多的位置。如果你想知道一个特定的gem被安装在哪里，你可以执行:

gem list -d <gemname>

示例输出:

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

我发现它有用的库文件的位置:

gem which *gemname*

你可以在命令提示符中通过运行gem帮助命令来检查它，然后选择合适的命令:

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    outdated               Display all gems that need updates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:~$ 

现在从上面我可以看到命令环境是有帮助的。所以我会这样做:

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:~$ 

最后告诉你你的要求，我会这样做:

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:~$ 

如果你正在使用RVM工具，你可以运行这个命令打印gem路径:

rvm gemdir

OR

echo $GEM_HOME

gem env列出了可以安装宝石的位置，但可以是10个或更多的位置。如果你想知道一个特定的gem被安装在哪里，你可以执行:

gem list -d <gemname>

示例输出:

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

你可以欺骗gem open显示gem路径:

VISUAL=echo gem open gem-name

例子:

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

它只是工作，没有第三方宝石是必要的。