convert size of image

convertsize.rb

#!/usr/bin/env ruby

if ARGV.size < 1
    puts "usage: <stdin list of files> | convertsize.rb <size>"
    exit 0
end

STDIN.each do |line|
    line.chomp!
    src = line
    tmp = line.sub(/^(.+)\.([^\.]+)$/) { |e|  "#{$1}_tmp_.#{$2}" }
    puts "convert -geometry #{ ARGV[0] } #{src} #{tmp}; rm #{src}; mv #{tmp} #{src}"
end