Error installing gems [closed]

Answer 1

Some gems rely on other gems to run, but haven't been setup correctly to automatically install them (ie they haven't had their dependencies correctly set).

You'll often only find out when you try to run them... just like this.

luckily the error message here makes it fairly clear that you need the "rspec" gem installed... and as you've already discovered, the solution is simply to install the missing gem.

Other gems aren't often as easy to figure out, but googling for the error message (or putting it up on StackOverflow) usually sorts it out pretty quick.

Answer 2

I had exactly the same error as this...

While installing Rails 3 my computer suffered a power outage. After restarting the computer and continuing the Rails 3 installation the process failed with this exact same error. The problem was due to the gem install cache which had corrupted / empty gem files. My solution was to clear this cache and run the install again, as follows:

1. Find out the location of your cache using gem env
2. List all the gems in that cache, e.g. ls -l /usr/lib/ruby/gems/1.8/cache/
3. Compare with successfully installed gems using gem list
4. Remove the gems from the cache list that are missing from the gem list e.g. using rm
5. I also had to remove some empty / corrupt gemspec files from the specification directory ls -l /usr/lib/ruby/gems/1.8/specifications/
6. Continue the installation, e.g. sudo gem install -v=3.0.6 rails --no-rdoc --no-ri

Hope this helps someone else who has a power outage or other external failure during a gem install process!