ruby: tcp socket sample(input line must end with \n)

tc.rb

#!/usr/bin/env ruby

# socket example - client side
# usage: ruby clnt.rb [host] port

require "socket"

if ARGV.length >= 2
  host = ARGV.shift
else
  host = "localhost"
end

print("Trying ", host, " ...")

s = TCPSocket.new("localhost", 3333)
print(" done\n")
print("addr: ", s.addr.join(":"), "\n")
print("peer: ", s.peeraddr.join(":"), "\n")

line = "a\n"
# must end with \n
p line


s.write(line)
print(s.readline)
s.close

ts.rb

# socket example - server side
# usage: ruby svr.rb

# this server might be blocked by an ill-behaved client.
# see tsvr.rb which is safe from client blocking.

require "socket"

gs = TCPServer.open(3333)
addr = gs.addr
addr.shift
printf("server is on %s\n", addr.join(":"))
socks = [gs]

loop do
  nsock = select(socks);
  next if nsock == nil
  for s in nsock[0]
    if s == gs
      ns = s.accept
      socks.push(ns)
      print(s, " is accepted\n")
    else
      if s.eof?
        print(s, " is gone\n")
        s.close
        socks.delete(s)
        # single thread gets may block whole service
      elsif str = s.gets
        s.write(str)
      end
    end
  end
end