tree.rb

#!/usr/bin/env ruby

# A poor man's implementation of the tree app    http://trac.macports.org/browser/trunk/dports/sysutils/tree/Portfile
# Written in part because I like the app and wanted that functionality on my school computer
# and in part because I was going through some videos about the command line, and wanted something interesting
# to put in my ~/bin dir 
#
# AUTHOR: Josh Cheek
#         5 July 2010



# print how to use it and exit
def usage
  puts "USAGE: #{File.basename __FILE__} [dir]"
  exit
end

# check arguments
usage if ARGV.length > 1 || ARGV.first.to_s[/^-/]

# extract the root directory (defaults to current dir, remove any trailing slash)
ROOT = (ARGV.first || '.').sub %r(/?$) , ''

# ensure the dir exists
usage unless File.directory? ROOT



def relative_path_print( prefixes , dir )
  fullnames = Dir.glob "#{dir}/*"
  fullnames.each_with_index do |fullname,index|
    basename = File.basename fullname
    if File.directory? fullname
      
      if index.next == fullnames.size                           # if it is the last dir, print with ` and below it is empty
        print prefixes.join , '`-- ' , basename , "\n"
        relative_path_print prefixes + ['    '] , fullname
      
      else                                                      # if it is not the last dir, print with |, and below it gets |
        print prefixes.join , '|-- ' , basename , "\n"
        relative_path_print prefixes + ['|   '] , fullname
      end
    
    elsif index.next == fullnames.size                          # if is last file, print with `
      print prefixes.join , '`-- ' , basename , "\n"
    
    else                                                        # if is just a file in the list, print with |
      print prefixes.join , '|-- ' , basename , "\n"
    end
  end
end

puts ROOT
relative_path_print [''] , ROOT