only-dir and with-dir

only-dir

#!/usr/bin/env ruby

require 'set'
base = ARGV.first || '.'
dirs = Set.new
$stdin.each_line do |line|
  dir = File.dirname(line)
  anc = []
  while dirs.add?(dir)
    anc << dir
    break if dir == base
    dir = File.dirname(dir)
  end
  puts anc.reverse unless anc.empty?
end

with-dir

#!/usr/bin/env ruby

require 'set'
base = ARGV.first || '.'
dirs = Set.new
$stdin.each_line do |line|
  dir = File.dirname(line)
  anc = []
  while dir != base && dirs.add?(dir)
    anc << dir
    dir = File.dirname(dir)
  end
  puts anc.reverse unless anc.empty?
  print line
end