gistfile1.txt

#!/usr/bin/env ruby
#
# Author: Anil Wadghule
#
# FRenamer: Renames image files for passed command line parameters
# Usage: frenamer . "the_dark_knight" 
# It renames image files in current directory with names like the_dark_knight_1.jpg, the_dark_knight_2.jpg ...
# 
# Installation:
# Copy it to your /usr/bin or any directory which is in your PATH
# chomod 777 it, to make it executable
#
#

Dir.chdir(ARGV[0])
cnt = 1
Dir["*"].each do |filename|
  puts "renaming"
  regex = /(?:.*)\.(png|jpg|gif)$/i
  fname = ARGV[1] || "picture"
  suffix = "#{fname}_#{cnt}"
  new_filename = filename.gsub(regex, "#{suffix}.\\1")  
  puts new_filename
  File.rename(filename, new_filename)
  cnt += 1
end