尽管安装了Rails，仍未找到“rails”命令

Question

I compiled and installed Ruby 2.2 from source to /usr/local/bin/ruby and /usr/local/bin/gem. (Due to project constraints I can't use RVM, it's a long story.)

I created symlinks to both of these in /usr/bin.

As root I ran:

gem install rails

and got:

Successfully installed rails-4.2.1
Parsing documentation for rails-4.2.1
Done installing documentation for rails after 0 seconds
1 gem installed

When I try to run Rails however, I get:

bash: rails: command not found

which rails also returns:

/usr/bin/which: no rails in (/sbin/:/bin:/usr/sbin:/usr/bin:/usr/local/bin)

My gem list is:

*** LOCAL GEMS ***

actionmailer (4.2.1)
actionpack (4.2.1)
actionview (4.2.1)
activejob (4.2.1)
activemodel (4.2.1)
activerecord (4.2.1)
activesupport (4.2.1)
arel (6.0.0)
bigdecimal (1.2.6)
builder (3.2.2)
bundler (1.9.4)
erubis (2.7.0)
globalid (0.3.5)
i18n (0.7.0)
io-console (0.4.3)
json (1.8.1)
loofah (2.0.1)
mail (2.6.3)
mime-types (2.5)
mini_portile (0.6.2)
minitest (5.4.3)
nokogiri (1.6.6.2)
power_assert (0.2.2)
psych (2.0.8)
rack (1.6.0)
rack-test (0.6.3)
rails (4.2.1)
rails-deprecated_sanitizer (1.0.3)
rails-dom-testing (1.0.6)
rails-html-sanitizer (1.0.2)
railties (4.2.1)
rake (10.4.2)
rdoc (4.2.0)
sprockets (3.0.3)
sprockets-rails (2.2.4)
test-unit (3.0.8)
thor (0.19.1)
thread_safe (0.3.5)
tzinfo (1.2.2)

Additionally, my gems environment looks like this:

RubyGems Environment:
  - RUBYGEMS VERSION: 2.4.5
  - RUBY VERSION: 2.2.2 (2015-04-13 patchlevel 95) [x86_64-linux]
  - INSTALLATION DIRECTORY: /usr/local/lib/ruby/gems/2.2.0
  - RUBY EXECUTABLE: /usr/local/bin/ruby
  - EXECUTABLE DIRECTORY: /usr/local/bin
  - SPEC CACHE DIRECTORY: /root/.gem/specs
  - SYSTEM CONFIGURATION DIRECTORY: /usr/local/etc
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /usr/local/lib/ruby/gems/2.2.0
     - /root/.gem/ruby/2.2.0
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - https://rubygems.org/
  - SHELL PATH:
     - /sbin/
     - /bin
     - /usr/sbin
     - /usr/bin
     - /usr/local/bin

Answer 1

...As root I ran...

And, what path does root think Ruby is in? Odds are really good it thinks Ruby is in /usr/bin, not /usr/local/bin since that path, /usr/local/bin, is probably not in root's path.

You could either prepend /usr/local/bin: to root's path temporarily, or you could use the gem in /usr/local/bin, which will know where to put gem files for that version of Ruby. I'd try:

sudo /usr/local/bin/gem install rails

which should install Rails for the new version of Ruby.

---

• SHELL PATH:
  • /sbin/
  • /bin
  • /usr/sbin
  • /usr/bin
  • /usr/local/bin

Notice the order that the path will be searched. /usr/bin is before /usr/local/bin . The purpose of /usr/local/bin is to provide a place for storing user-wide locally installed executables. Typically that is the place you install modified versions of executables when you want to override the default /usr/bin executables' behavior, such as if you wanted a new Ruby to run on your machine.

Instead of what you're using, your /usr/local/bin should be before /usr/bin in your PATH definition. That will definitely cause different search behavior, especially for which , but it's not guaranteed to fix the problem you're seeing.

gem install rails would find the gem in /usr/bin, not in /usr/local/bin and would install Rails into that same Ruby's path.

which searches the path, so check to see if there is a rails command in /usr/bin:

ls /usr/bin/rails

If it exists, you probably need to rebuild the hash used for fast searching. I think that'd be rehash rails but my memory is fuzzy on that one.