rubygems error installing rails - ruby

I get this error when trying to install ruby gems on my amazon instance. Can anyone explain?
ubuntu#ip-myinstance:~$ sudo apt-get install rubygems
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package rubygems is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
ruby
E: Package 'rubygems' has no installation candidate
I didn't understand that message. I was following directions from http://www.frontcoded.com/rails-on-amazon-ec2-ubuntu.html which says to do that. Also I tried
which rubygems
And that came out blank. If possible I would like to take down this question to stop the negative votes. Thank you.

You are trying to install the wrong package. In modern Ruby, rubygems come as part of it. The message you got also says so.
Even if there were a problem on the server side, not being able to download something through apt-get has nothing to do with whether rubygems site is down.
The message you got, which gives you an alternative suggestion, indicates that the relevant site (apt-get) is not down.
You can check the status of certain websites by using services like this.

Related

Generating RDOCs for locally installed gems

I am trying to contribute to a gem I recently took interest in - Nesta. The developer has done a great job in creating one of the lightest, thinest CMSs you can find and I want to document it. I have read through the code and commented on a few methods to the best of my knowledge.
However, I seek to test this out locally by calling gem server and seeing the changes on my machine before pushing it online.
Things I have tried:
Manual edit.
Documented the file.
Fired up gem server.
Using the gem tool.
Documented the file.
Ran gem rdoc nesta --rdoc
Restarted gem server
All to no avail. Please help.
Thank you.
You can preview generated html pages without installing a modified version of the gem on your machine. Add this to nesta's Rakefile:
require 'rake/rdoctask'
Rake::RDocTask.new('doc') do |i|
i.rdoc_files = FileList['lib/**/*']
end
and type rake doc. Then view generated html/index.html file.
Are you sure you've installed the version that you've modified, not the original version?
If you've installed the modified version, but have forgotten to install the rdoc, see Can you install documentation for existing gems?

gem command . What does that mean

Sometimes I have seen following code.
gem 'factory_girl','= 1.2.3'
require 'factory_girl'
I tried to look at gem doc but could not find answer to the question of what does the first line do in code above?
What you're looking for in the gem docs is about Coding with Rubygems.
The first line basically says "Hey, go get this gem with this version" from the install directory for gems and load it into the environment. This is mainly to help you add version dependencies to your requires instead of just doing require 'factory_girl' by itself.
Edit: To add on to Jörg's point below, I thought that Ryan Tomayko had a pretty good short and sweet article about why doing this is "wrong".
As #theIV already explained, this activates the factory_girl gem, using exactly (because of the = sign) version 1.2.3.
Note, however, that this is very bad practice and should never be done. If you activate gems manually inside your code, it means that people who do not use RubyGems can no longer use your code.
RubyGems is a package manager. Your code should never care about what package manager was used to install it. Some people prefer RubyGems, some dpkg/APT, some RPM/YUM, some RPM/APT, some RPM/URPMI, some RPM/YaST2, Portage, FreeBSD ports, pkgsrc, MacPorts, slashpackage, CoAPP, Conary, Slackware. There's tons of them. Some people like not to use any package manager at all. Or, they use RubyGems just for downloading, but then unpack the gem into their vendor directory.
All of this cannot possibly work, if you use the gem method in your code.

Showing all a Gem's build flags

This is more a curiosity than necessity question. I've just installed nokogiri again with RubyGems and it is saying "WARNING: Nokogiri was built against LibXML version 2.7.5, but has dynamically loaded 2.7.6" This is easy enough to fix, but it lead to a more general question: how do I see all the configuration options for a rubygem before installing it?
I found the easiest way I know how is to visit the gem folder an run "ruby nokogiri-0.0.0/ext/nokogiri/extconf.rb -h" and that shows me it, but there has to be an easier way, right?
I was expecting some kind of "sudo gem install nokogiri -- --help" command that would show the build flags. I've searched around a bit but didn't see anything, anybody know how to do this before I go digging into RG's source :)?

How can I get past "http://gems.rubyforge.org/ does not appear to be a repository" error message

Question 828421 asked similar question, but received only one real answer (update rubygems) and that attempt results in the same error.
Ruby version 1.9.1.p243 on Windows. Included Gem, version 1.3.5.
Never installed any gems before; never did any special config for this Ruby.
Ruby itself works, as does irb, and "gem" operates but can't do install (and maybe other ops).
Tried this (from a book):
gem install rspec
Got this:
ERROR: http://gems.rubyforge.org/ does
not appear to be a repository
ERROR: While executing gem ...
(Gem::RemoteFetcher::FetchError)
SocketError: getaddrinfo: The storage control blocks were destroyed.
(http://gems.rubyforge.org/yaml)
When I go to that URL (without "yaml") using MSIE7, I get a page titled "Gemcutter | awesome gem hosting" and have no problem wandering around that site. So I don't -think- it's a proxy problem (though this is all from inside corporate firewall/proxies/etc).
When I go to that URL -with- "yaml", it goes to "http://production.s3.rubygems.org/yaml" and shows what I assume is an update specification page, starting with this:
--- !ruby/object:Gem::SourceIndex
I didn't destroy any "storage control blocks". So what is preventing gem from installing a gem?
Web search shows MANY people having this same problem over a long span of time, but I have yet to see anyone say "It's because of THIS, so do THIS to fix it." Well, someone suggested updating "gem", but trying that gets same error.
Help please?
Your browser might be using system-wide proxy settings or some sort of automatic configuration. The gem command probably doesn't. I'm behind an university proxy and I can't install/update any gems normally, but can access everything with my browser. To install gems, I normally create a tunnel to my server so I can bypass the proxy server.
This might help you to configure the proxy settings for the gem command: How do I update Ruby Gems from behind a Proxy (ISA-NTLM)
Sample:
sudo gem install nifty-generators -p http://proxy:port
It works well.
If your proxy requires authentication, then use:
gem install --http-proxy http://USERNAME:PASS#HOST:PORT gem_name
This can "at times" mean that for some reason rubygems.org is down currently, and so your local "invisible proxy" is returning you a 404 or what not.
#Tomas Markauskas didn't work for me because i'm not behind a proxy. And I didn't find a solution anywhere, I tried disable my AV and firewall, didn't
This was the solution for me:
gem install rails -r -w -p
Hope this will help people with the same problem.
EDIT: I have Windows 7 64bit.

Ruby Gems Problem: uninitialized constant Gem::GemRunner

I had a rails 2.2 app running, when I tried to add the latest rspec plugin to it. I did that checking it from github with the script/plugin install command. That made some rake task to stop working, I googled for a while and found that I had to upgrade RubyGems. I did that and got the following error:
uninitialized constant Gem::GemRunner
It was a small and simple app under version control, so I erased everything, and apt-get remove ruby and rubygems, and reinstalled everything once again (doing apt-get install ruby, rubygems)
The problem it's still there, and I can't figure how to solve it. I'm quite new with Ubuntu, so maybe I'm not removing the packages really? (it takes very little time to execute the apt-get removes, so I'm not very confident)
What am I doing wrong? Is that a good way to do a 'clean start' (removing via apt and then reinstalling?)
PS: I've read that the problem is solved by modifiing framework.rb, but I cant find that file in the location that the author states...
I have a blog post that solves this issue.
It's because it's still trying to use the old gem executable, so you just symbolically link the new one (gem1.8) in place of the old one.

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