<p>I want my Ruby program to do different things on a Mac than on Windows. How can I find out on which system my program is running?</p>

Either
```
```
irb(main):002:0> require 'rbconfig'
=> true
irb(main):003:0> Config::CONFIG["arch"]
=> "i686-linux"
```
```
or
```
```
irb(main):004:0> RUBY_PLATFORM
=> "i686-linux"
```
```