Simple script that I use for mergin GPX tracks.

gpx_joiner.rb

#!/usr/bin/env ruby

require "nokogiri"
require "pathname"
require "date"

gpx_root_folder = "/"+["Users", ENV["USER"], "mainnav-tracklogs"].join("/")

if ARGV[0].nil? or ARGV[1].nil?
  puts "Missing dates!"
end

diff_dates = []
(Date.strptime(ARGV[0],"%y-%m-%d")).upto(Date.strptime(ARGV[1],"%y-%m-%d")) do |date|
  diff_dates << date.strftime("%y-%m-%d")
end

files = Dir.glob(gpx_root_folder+"/*/*").select do |v|
  m = /track_(\d.*)-(\d.*)-(\d.*)_/ =~ v
  diff_dates.include? "#{Regexp.last_match[1]}-#{Regexp.last_match[2]}-#{Regexp.last_match[3]}"
end

files.sort! do |a,b|
  p_a = /track_(\d.*)-(\d.*)-(\d.*)_/ =~ a
  d_a = Date.strptime("#{Regexp.last_match[1]}-#{Regexp.last_match[2]}-#{Regexp.last_match[3]}","%y-%m-%d")
  p_b = /track_(\d.*)-(\d.*)-(\d.*)_/ =~ b
  d_b = Date.strptime("#{Regexp.last_match[1]}-#{Regexp.last_match[2]}-#{Regexp.last_match[3]}","%y-%m-%d")
  d_a <=> d_b
end

# Merge
f_name = "merged_#{ARGV[0]}_to_#{ARGV[1]}.gpx"

puts "Building #{f_name}"

f_out = File.open(f_name,"w")

f_out.write '<?xml version="1.0" encoding="UTF-8"?>
<gpx creator="Oto Brglez - gpx_joiner" version="1.1"
xmlns="http://www.topografix.com/GPX/1/1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
'

files.each do |path|
  puts "Working with: #{path}"
  c_file = File.open(path)
  doc = Nokogiri::XML(c_file)
  f_out.write(doc.xpath("//n:trk","n" => "http://www.topografix.com/GPX/1/1").to_s)
  c_file.close
end

f_out.write("</gpx>");
f_out.close

puts "Done."