ruby global variables

gistfile1.rb

$: contains an array of paths that your script will search through when using require
>>$:
#=> [".", "/Users/path/.ruby", "/test/path"]

$0 script name

$* shorter for ARGV

$? returns the exit status of the last child process to finish
>>`pwd`
#=> '/path/to/'
>> $?
=> #<Process::Status: pid=17867,exited(0)>
>> `fake command` # This will fail
(irb):7: command not found: fake command
=> ""
>> $?
=> #<Process::Status: pid=17871,exited(127)>

$$ returns the process number of the program currently being ran.

(tto be con)