Instant Ruby CGI server

server.rb

#!/usr/bin/env ruby
require "webrick"

server = WEBrick::HTTPServer.new(Port: 8080, DocumentRoot: Dir::pwd)
trap("INT") { server.shutdown }
server.start

tail.cgi

#!/usr/bin/env ruby
require "cgi"

NUM_LINES    = 20
FILE_TO_TAIL = "/var/log/system.log"
COMMAND      = "| tail -#{NUM_LINES} #{FILE_TO_TAIL}"

cgi = CGI.new
open(COMMAND) {|io| cgi.out("text/plain", &io.method(:read)) }