如何告诉 bundle install 在我的 PATH 上使用 Ruby 版本？

Question

我正在尝试在 Debian 上安装我的 Rails 5 项目。使用或不使用sudo 运行bundle install 都会导致错误，抱怨没有适当的Ruby 版本，即使在我运行ruby -v 之后，您可以看到版本是2.4。如何将bundle install 指向正确的版本？

$ sudo bundle install
[sudo] password for myuser:
Don't run Bundler as root. Bundler can ask for sudo if it is needed, and installing your bundle as root will break this application for all non-root users on this machine.
Your Gemfile lists the gem jquery-rails (>= 0) more than once.
You should probably keep only one of them.
While it's not a problem now, it could cause errors if you change the version of just one of them later.
Fetching gem metadata from https://rubygems.org/........
Fetching additional metadata from https://rubygems.org/..
Using rake 12.0.0
Using concurrent-ruby 1.0.5
Using i18n 0.8.6
Using minitest 5.10.3
Using thread_safe 0.3.6
Using tzinfo 1.2.3

Gem::InstallError: activesupport requires Ruby version >= 2.2.2.
An error occurred while installing activesupport (5.0.4), and Bundler cannot continue.
Make sure that `gem install activesupport -v '5.0.4'` succeeds before bundling.

$ ruby -v
ruby 2.4.0p0 (2016-12-24 revision 57164) [armv6l-linux-eabihf]

在没有sudo 的情况下运行：

$ bundle install
Your Gemfile lists the gem jquery-rails (>= 0) more than once.
You should probably keep only one of them.
While it's not a problem now, it could cause errors if you change the version of just one of them later.
Fetching gem metadata from https://rubygems.org/........
Fetching additional metadata from https://rubygems.org/..
Using rake 12.0.0
Using concurrent-ruby 1.0.5
Using i18n 0.8.6
Using minitest 5.10.3
Using thread_safe 0.3.6
Using tzinfo 1.2.3

Gem::InstallError: activesupport requires Ruby version >= 2.2.2.
An error occurred while installing activesupport (5.0.4), and Bundler cannot continue.
Make sure that `gem install activesupport -v '5.0.4'` succeeds before bundling.

$ ruby -v
ruby 2.4.0p0 (2016-12-24 revision 57164) [armv6l-linux-eabihf]

Answer 1

当您调用 bundle 时，首先bundle 本身会在$PATH 中解析。您可以通过键入whereis bundle 或which bundle 来检查其可执行文件的位置。就我而言（Ubuntu 16.04），它位于/usr/local/bin/bundle。

如果我们执行cat /usr/local/bin/bundle，我们会得到这个可执行文件的内容：

$ cat /usr/local/bin/bundle
#!/usr/bin/ruby2.4
#
# This file was generated by RubyGems.
#
# The application 'bundler' is installed as part of a gem, and
# this file is here to facilitate running it.
#

require 'rubygems'

version = ">= 0.a"

if ARGV.first
  str = ARGV.first
  str = str.dup.force_encoding("BINARY") if str.respond_to? :force_encoding
  if str =~ /\A_(.*)_\z/ and Gem::Version.correct?($1) then
    version = $1
    ARGV.shift
  end
end

load Gem.activate_bin_path('bundler', 'bundle', version)

如您所见，它是一个普通的 Ruby 脚本，最上面的一行 (#!/usr/bin/ruby2.4) 设置解释器来执行它。

我想，在您的情况下，使用的是旧 Ruby 版本，因为如果您在安装 2.4.0 之前在系统中有 Ruby，则 gem 的可执行文件没有更新为 2.4，并且还使用旧 Ruby版本。你可以通过which gem（对我来说/usr/bin/gem）和cat检查文件内容来检查这一点。

之后，您可以通过键入whereis gem 来检查gem 的可用可执行文件：

$ whereis gem
gem: /usr/bin/gem /usr/bin/gem2.2 /usr/bin/gem2.4

然后您可以通过键入 gem uninstall bundler 删除捆绑程序（这也应该删除它的可执行文件）并使用正确的 gem 再次安装它，执行：

/usr/bin/gem2.4 install bundle

这应该可以解决问题，因为在 bundler 的可执行文件中，您将获得 Ruby 2.4 作为解释器。

update-alternatives 命令也可以用于这种情况。

如您所见，这太让人头疼了，所以我的建议是要么使用 Ruby 版本管理器（rvm、rbenv 等），要么每台机器只有一个 Ruby 版本。

Answer 2

gem install rails --version 5.0.0