Shebang (Unix)

exec shell

http://en.wikipedia.org/wiki/Shebang_(Unix)

exec.csh

#!/bin/csh

# http://en.wikipedia.org/wiki/C_shell

set i = 2
set j = 1
while ( $j <= 10 )
   echo '2 **' $j = $i
   @ i *= 2
   @ j++
end

exec.rb

#!/usr/bin/env ruby

puts "#{RUBY_VERSION}-p#{RUBY_PATCHLEVEL}"