cheat sheets.

--- grep version 2	Thu Aug 16 18:25:53 +0000 2007
+++ grep version 3	Tue Jul 08 09:11:09 +0000 2008
@@ -1,33 +1,34 @@
 Overview
 ========
 grep searches for lines matching a pattern.
 
 $ grep [OPTION]... PATTERN [FILE] ...
 
 PATTERN can be a normal string or a regular expression. For more on regular
 expressions see:
 $ cheat regexp
 
 Get full help:
 $ grep --help
 
 Basic Usage
 ===========
 $ grep index *.rb
 admin_controller.rb:  def index
 store_controller.rb:  def index
 store_controller.rb:    redirect_to_index 'Invalid product'
 store_controller.rb:      redirect_to_index "Your cart is currently empty."
 
 
 Useful Options
 ==============
 -h:   suppress file names in output
 -w:   restrict search to whole words only
 -c:   displays count of matching lines in each file, not the lines themselves
       (note this is not the same as $ grep index *.rb | wc -l)
 -i:   ignore case
 -l:   list only file names containing matching lines
 -n:   precede each line with the line number where it was found
 -v:   display all lines NOT matching pattern
+-C:   Display NUM lines of context either side of matches