system-getifaddrs

The creator of system-getifaddrs, Bruno Coimbra, is so awesome! He helped me fix the problems I had here.

Setting up system-getifaddrs:

Inside the system-getifaddrs directory, I did:

$ sudo gem install system-getifaddrs

[sudo] password for haoqili:
Fetching: system-getifaddrs-0.1.1.gem (100%)
Building native extensions. This could take a while...
Successfully installed system-getifaddrs-0.1.1
1 gem installed
Installing ri documentation for system-getifaddrs-0.1.1...
Installing RDoc documentation for system-getifaddrs-0.1.1...

Then I did:
$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'system/getifaddrs'
=> true
irb(main):003:0> p System.get_ifaddrs

{:wlan0=>{:inet_addr=>"18.111.61.140", :netmask=>"18.111.61.140"}, :vmnet1=>{:inet_addr=>"172.16.76.1", :netmask=>"172.16.76.1"}, :vmnet8=>{:inet_addr=>"172.16.197.1", :netmask=>"172.16.197.1"}, :lo=>{:inet_addr=>"127.0.0.1", :netmask=>"127.0.0.1"}}
=> nil

me: how come eth0 is not in the list?
Bruno: are you connected on wireless?
me: I'm on wireless
Bruno: you are using
           eth0 should be down


Making test.rb work. Add the first line, so it's like:
1 require "rubygems"
2 require "pp"
3 require "system/getifaddrs"
4 pp System.get_ifaddrs

Where pp is for "pretty print".
$ ruby test.rb

{:wlan0=>{:inet_addr=>"18.111.61.140", :netmask=>"18.111.61.140"},
:vmnet1=>{:inet_addr=>"172.16.76.1", :netmask=>"172.16.76.1"},
:vmnet8=>{:inet_addr=>"172.16.197.1", :netmask=>"172.16.197.1"},
:lo=>{:inet_addr=>"127.0.0.1", :netmask=>"127.0.0.1"}}

Without the first line, the result would be as below. I need the "rubygems" because I am running system-wide ruby instead of rvm, changed to it here. (which ruby, gives "/usr/bin/ruby")

test.rb:2:in `require': no such file to load -- system/getifaddrs (LoadError)
from test.rb:2

Where is the *.gem file?
me: is system-getifaddrs a ruby gem?
Bruno: yep
me: how come it doesn't have a *.gem file anywhere?
Bruno: ah, on github have only source files
me: so the *.gem file is not necessary for it to run?
Bruno: *.gem file is the package file like deb packages for debian
             after installing, files are unpacked under ruby lib dir and gem file is discarted
me: so, on github you put the state after unpackaging, that's why .gem doesn't need to be there
Bruno: nope, on github is development sources. with that sources you can packaging its into a gem file