...here is the stack:

# gem list --backtrace

*** LOCAL GEMS ***

ERROR: While executing gem ... (NoMethodError)
undefined method 'loaded_from=' for nil::NilClass
/usr/lib/ruby/site_ruby/1.8/rubygems/cache.rb:32:in `from_installed_gems'
/usr/lib/ruby/site_ruby/1.8/rubygems/cache.rb:29:in `each'
/usr/lib/ruby/site_ruby/1.8/rubygems/cache.rb:29:in `from_installed_gems'
/usr/lib/ruby/site_ruby/1.8/rubygems/cache.rb:28:in `each'
/usr/lib/ruby/site_ruby/1.8/rubygems/cache.rb:28:in `from_installed_gems'
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:97:in `cache'
/usr/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:354:in `execute'
/usr/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:443:in `execute'
/usr/lib/ruby/site_ruby/1.8/rubygems/command.rb:49:in `invoke'
/usr/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:82:in `process_args'
/usr/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:55:in `run'
/usr/lib/ruby/site_ruby/1.8/rubygems/gem_runner.rb:9:in `run'
/usr/bin/gem:6

-----Messaggio originale-----
Da: Jim Weirich [mailto:jim / weirichhouse.org]
Inviato: marted13 luglio 2004 18.44
A: ruby-talk ML
Oggetto: Re: R: rubygems undefined method 'loaded_from=' for
nil::NilClass



Petrucci Fabio said:
> You are right... the command was :
>
> # gem install log4r-1.0.5.gem

Good.  I was worried about a version mismatch.

> now running this command:
>
> # gem list --traceback gives...
>
> ERROR: While executing gem ... (OptionParser::InvalidOption)
> 	invalid option: --traceback

Oops.  That was my fault.   I was working from memory instead of checking
the docs.

The option is --backtrace.  Please try it again.

Sorry for the confusion.

-- 
-- Jim Weirich     jim / weirichhouse.org    http://onestepback.org
-----------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct,
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)