Disobedient 'gem env' Causing Rails "undefined method `gem' "

rubyonrails-talk
1

I'm setting up on a textdrive shared host, and have installed my gems to a local directory called 'gems'. I did this by installing the gems on my ubuntu 7.04 system and tar'ing up the 'gems' to a like-named directory on the 'gilford' (FreeBSD 5.3) shared host. (a trick required because 'gem update' or 'gem install' busts txd's memory limit during a zlib inflate of the gem repository hash - that is, memory allocation fails for even the smallest of gems)

After setting my GEM_PATH and GEM_HOME so that 'gem query' reports _only_ my locally installed gems (as expected), and this test:

[xxx@gilford ~]$ gem list rubygems    *** LOCAL GEMS ***    rubygems-update (0.9.2)        RubyGems Update GEM

reports exactly what I expect, I next try 'gem env', which nonetheless reports a back-rev gem version( ! ):

[xxx@gilford ~/local]$ gem env Rubygems Environment:   - VERSION: 0.8.11 (0.8.11)   - INSTALLATION DIRECTORY: /users/home/xxx/gems   - GEM PATH:      - /users/home/xxx/gems      - /users/home/xxx/local/lib/ruby/site_ruby/1.8   - REMOTE SOURCES:      - http://gems.rubyforge.org

(note that I have removed the 'gilford' system's gem path altogether, in desperation. I'm trying to avoid all of txd's gems, so that I am certain that only my local stuff is included)

So I download the rubygems-0.9.2.tgz and stick it in a 'local' directory, and adjust the two GEM paths above, plus my normal shell PATH and LD_LIBRARY_PATH to use the 'local' bins and libs first. But I still get 'gem env' -> 0.8.11

The actual 'gem' file in the 'local/bin' directory is simply some Ruby that does:

require 'rubygems' Gem.manage_gems

with a few more lines. Surely these lines are run with either GEM_PATH or the .gemrc path? And I think both of these are right: 'gem query' proves 'GEM_PATH' is working, and the next paragraph shows .gemrc works as well.

(I also have a consistent .gemrc in my home dir. According to Jim Weirich's note from Apr 3 2006, I think I'm doing the right thing: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/187403

In short: "All gems use GEM_PATH, except for 'gem', which uses .gemrc." This behavior is supported by a test in which I add or subtract 'gilford's' gem path from my .gemrc: and as expected, my 'gem env' output shows only the lines specified in .gemrc.

The reason I care so much about what 'gem env' says is because when I type "rails -v" I get: /users/home/xxx/gems/bin/rails:15: undefined method `gem' for main:Object (NoMethodError)

which various posts say results from running current 'rails' with a back-rev 'gem'. The shared host 'gilford' is running Ruby 1.8.4

2

'gemwhich rubygems' returns -> /usr/local/lib/ruby/site_ruby/1.8/ rubygems.rb BAD!

But my .gemrc explicitly specifies a gempath of /home/users/xxx/local/ lib/ruby/site_ruby/1.8 , and this directory does in fact have a different version of 'rubygems.rb'.

So why does 'gemwhich rubygems' find a file that is not on any path I know of? ('require rubygems' is supposed to employ the same lookup algorithm as 'gemwhich')

Can anyone explain what it is doing?

3

'rubygems' itself is found via a Ruby $LOAD_PATH lookup.

As the PickAxe book explains, this can be set by a 'ruby -I xxx' invocation. But in the case of 'gem' itself, or of 'rails', there is no command line '-I' option.

So the library lookup path is specified by $RUBYLIB. This is the Ruby analog to C's $LD_LIBRARY_PATH

My .bash_profile now contains:

export RUBYLIB=$HOME/gems/local/lib/site_ruby/1.8 export GEM_PATH=$HOME/gems export GEM_HOME=$HOME/gems

If I want some of txd's stock (old) gems, I'd add their path as well.kk See http://rubygems.org/read/chapter/15