$ rails _3.0.5_ new depot
rubygems.rb:244:in `bin_path': can't find gem railties (["3.0.5"]) with executable rails (Gem::GemNotFoundException)
出错
重装了rails sudo gem install rails --version 3.0.5后
$ rails _3.0.5_ new depot
dependency.rb:247:in `to_specs': Could not find rails (= 3.0.5) amongst [bundler-1.6.2, bundler-unload-1.0.2, executable-hooks-1.3.1, gem-wrappers-1.2.4, i18n-0.6.9, json-1.8.1, minitest-5.3.3, minitest-1.6.0, rake-0.8.7, rdoc-4.1.1, rdoc-2.5.8, rubygems-bundler-1.4.3, rvm-1.11.3.9, thread_safe-0.3.3, tzinfo-1.1.0] (Gem::LoadError)
from /usr/lib/ruby/1.9.1/rubygems/dependency.rb:256:in `to_spec'
from /usr/lib/ruby/1.9.1/rubygems.rb:1231:in `gem'
from /usr/local/bin/rails:22:in `<main>'
运行命令rvmsudo gem install rails --version 3.0.5之后
Warning: can not check `/etc/sudoers` for `secure_path`, falling back to call via `/usr/bin/env`, this breaks rules from `/etc/sudoers`. Run:
export rvmsudo_secure_path=1
to avoid the warning, put it in shell initialization file to make it persistent.
In case there is no `secure_path` in `/etc/sudoers`. Run:
export rvmsudo_secure_path=0
to avoid the warning, put it in shell initialization file to make it persistent.
rails's executable "rails" conflicts with railties
Overwrite the executable? [yN] y
Successfully installed rails-3.0.5
Parsing documentation for rails-3.0.5
Done installing documentation for rails after 0 seconds
1 gem installed
如果不行，bundle install, 再运行一次rvmsudo gem install rails --version 3.0.5
原理：
安装时路径出现了问题
I try to explain this a bit because of the upvotes:
This basically is a path issue. If you set up gems via gem install, they mostly likely will be in another directory (e.g. /usr/local/) compared to gems set up via bundler (where you can override it with --path). Using sudo may also set them up into another directory since sudo starts a subshell which has a different environment then. This is why you have rvmsudo.
If you want to see the differences, compare $PATH, $GEM_HOME, $GEM_PATH and $BUNDLE_PATH when echoing directly, with sudo and with rvmsudo.